I'd have to think a bit longer about new things, but the current things that most annoy me on a daily basis are..
In the track inspector the clip info tab doesn't shrink back the inspector like the track info and PC tabs do. ie. if I have the inspector just showing the track info and not the bus also, clicking on the PC tab will resize the UI to use the PC. Click on it again when your done and it reverts to the previous state, TI tab is the same, but Clip tab opens but never closes. Always having to click on one of the other two tabs and then close that instead. A minor thing maybe, but it's really annoying and I would imagine a relatively simple fix as it works fine in X3, but somewhere along the line a Platinum update broke it. I can't say when exactly because my first installed Platinum version was 2016.12 and it was already broken by then.
Lack of a solo button on pro-channel eq.
The undo bug - Edit>Undo doesn't show the last action, but the one before it. Again something that got broken along the way and repeatedly ignored.
New features that have come to mind while writing...
Console view folders - a user option to have the same effect on the console view when a track folder is closed.
Ability to reorder the synths in the synth rack, just for the sake of tidiness really. On larger projects it would be nice to be able to see all of the instances of the same synth displayed adjacently rather than just in whatever order they were added to the project.
The browser could do with some love - things like the abilty to show the UI of the synth/fx as a thumbnail (whispers quietly........like in studio one).