The update will be live on the main web site tomorrow. It is currently up on Landoleet. It's v5.50a on LOL. It is my understanding that it will say v5.50 on the main web site, but the executable will say v5.50a to avoid ambiguity.
https://www.landoleet.org/ Change Log
v5.50a - September 16 2017
+ Automation: fix combining of trim/main volume envelope with different scales
# Automation items: ensure item edge points are square-shaped for mute envelopes
# Envelopes: fix insert 4 env points before an AI [p=1885418]
# Envelopes: fix possible crash when clearing envelope from envcp
# linux: improve Python auto-detection
changelog for 5.50:
+ Actions: automatically make capitalization consistent for non-localized action description strings
+ Audio: allow frequencies up to 100MHz when using dummy audio driver [t=195153]
+ Audio: avoid changing device samplerate to default samplerate when loading projects [t=193651]
+ Audio: add option to flash transport status yellow on possible audio device underrun
+ Audio: improve various playback/recording behaviors when using background project tabs [t=193849]
+ Automation items: add automation item support, to contain, move, and transform portions of envelopes
+ Automation items: items mask the baseline envelope, but overlapping items all affect playback
+ Automation items: items may be pooled or unpooled, looped, stretched, skewed, and phase-shifted
+ Automation items: items may be named, saved, and loaded
+ Automation items: support separate baseline, amplitude, and looping for individual instances of pooled automation items
+ Automation items: alt+drag in envelope lane (by default) to draw automation items
+ Automation items: add automation item and automation item edge mouse modifier contexts
+ Automation items: add actions to insert, duplicate, split glue, delete, etc
+ Automation: prevent latency adjustment when playback is stopped [t=193321]
+ Configuration: support import/export of more configuration files
+ Envelopes: add envelope lane mouse modifier context, deprecate preference to respect envelope segment modifiers in envelope lane
+ Envelopes: remove envelope lane click mouse modifier context, add envelope lane double-click context
+ Envelopes: add mouse modifier to freehand draw envelope points respecting snap
+ Envelopes: add actions to reverse envelope points, reduce number of points by half, insert envelope point ignoring snap
+ Envelopes: fix a few non-working send envelope menu items [t=190902]
+ Envelopes: add option to prevent mouse edits of single envelope points from moving past other envelope points
+ Envelopes: preserve envelope curvature during "move envelope segment preserving edge points" edit
+ Envelopes: preserve envelope curvature when moving points with media items, or within time selection
+ Envelopes: preserve envelope curvature at time selection edges when initiating envelope segment edit within time selection
+ Envelopes: improve behavior when freezing/unfreezing with send and pre-fx envelopes [t=195398]
+ Envelopes: fix initial value when auto-adding FX parameter envelope [t=192204]
+ FX: improve support for wet/bypass/VST3 parameter IDs on MIDI learn, TCP knobs
+ FX: do not auto-increase track channel count when loading FX chains that have multichannel FX but were saved from stereo tracks
+ FX: fix potential bugs relating to bypass/wet envelopes when loading automation and FX parameter counts change
+ FX: fix issues related to user-preset navigation [t=195699]
+ FX: add ReaCast, a shoutcast/icecast source plug-in
+ FX: improve ReaEQ/ReaXcomp analyzer accuracy [t=194328]
+ FX: fix project save of JSFX preset names that contain spaces
+ FX: add mix-in and auto-update options to allow some spectral smearing capabilities for JSFX spectral_hold
+ FX: improve display updates for some JSFX scripts
+ Grid: sanitize grid values on project load/entry [t=190108]
+ LAME: bundle libmp3lame 3.99.5
+ MIDI: restore keyboard focus to piano roll after changing CC lane via dropdown
+ MIDI: fix action to explode MIDI by pitch (and some related behaviors) [t=190905]
+ MIDI: fix project MIDI export when project start time is not zero [t=194713]
+ MIDI: fix project MIDI export SMPTE time when using ND timecode [t=194710]
+ MIDI editor: handle click on track title exactly like a click on the activate icon in the MIDI track list
+ Metronome: support triplets in metronome pattern [t=192992]
+ NINJAM: improve cross-platform compatibility of clipsort.log import
+ Notation editor: fix PDF export when "bracket tracks by folder" option enabled [p=1844292]
+ Notation editor: preserve notation for non-displayed notes when edits are made with channel filter active [t=185286]
+ Pan: allow very small track pans in fine adjustment mode
+ Pan: display sub-1% pans with increased precision
+ Pan: decrease media item properties pan snap-to-center threshold [t=190557]
+ ReaScript: improve undo/update behavior for InsertTrackAtIndex(), DeleteTrack() [t=135573]
+ ReaScript: avoid setting console focus on reaper.ShowConsoleMsg("")
+ ReaScript: improve display updates for some scripts
+ Sends: set focus for temporary single-send adjustment windows
+ Spectrogram: add spectral editing support, action to insert new edit regions [rv=vSBO_VC9q3E]
+ Theme: fix incorrect separators with grouped tracks [p=1874859]
+ Undo: improve undo efficiency
+ Undo: automatically make capitalization consistent for non-localized undo point description strings
+ Undo: fix behavior when reordering FX with automation [t=191588]
+ Undo: fix behavior with FX TCP parameters and learn [p=1845984]
+ Undo: fix parameter modulation settings
+ Undo: fix behavior when modifying stretch markers via swing grid
+ VST: support VST3 extended functionality with Softube Console 1
+ VST: improve macOS bundleExit VST3 compatibility
+ VST: improve resize behavior of various plug-ins [t=193099]
+ VST: send 10 channel speaker arrangements as user-defined [t=194176]
+ VST: use VST3 parameter IDs for tracking envelopes/parameter modulation across sessions
+ Video: fix rounding behavior with alpha-blended gfx_xformblit/gfx_deltablit
+ Web Interface: add fancier.html
+ Windows: increase FLS slots available on x64 for improved plug-in compatibility
+ Windows: support receiving ASIO overload notifications
+ macOS: add CoreAudio option to ignore project samplerate
+ macOS: support receiving CoreAudio overload notifications
+ macOS: improve scroll behavior of non-REAPER windows on 10.11+ [t=195544]
+ macOS: improve mixer drag and drop behavior [t=190761]
+ macOS: preserve parameter modulation window position when auto-resizing