Hi Fabio,
I had similar problems with my Sonar Platinum Manchester edition, last one lifetime released. Also AR TG Mastering would only work on left channel. I finally downloaded the new version of Cakewalk by BandLab and seems to have solved most problems. I found I had to click on the mono/stereo button a couple of times to get it to work on both Left & Right channels. Install was painless. It used all the existing paths, except needed to copy my templates over to the new 'Cakewalk Core' directory. It found almost all my old CW Sonar (since Studio 8/2007) plugins & worked, did loose a couple though. Also there is an upgrade from Waves for TG AR Mastering if U haven't already done so.
There is a few other improvements in the BandLab version. So I'm retiring my Platinum version and going with the new free one by BandLab. Just a few days ago.
'The Outlet for Creative Bent Studio' -
System: Win 10 Pro x64, i7Core 6700K OC'd @4.7, 64Gb Ram @ 2133, 10-Tb storage (including 4-Tb USB3 backup) 4-Gb Video, Dual monitors 27" & 19", USB: Audio - Focusrite Scarlett 18i20, MIDI - MUTO Express 128, 10 USB MIDI inputs devices; highlights - Oxygen 88, Alexis Wireless Keytar, Maschine Micro II, Novation Compact 49SL, 3 - 61 key, 25 key, Korg padKontrol, Akai MPD18, & real Roland SH-201 Synth, 10 monitor speakers, wired & wireless headphones, 6 mic's (1 wireless)
Software: Sonar 10 year Collection, Rapture Pro (9,000+ sound bank), Zeta 2, NI Komplete 10 Ult plus many additional Kontakt 5 & Reaktor 5 modules, AAS Modelling Collection I&II, BFD 3 (2,000 kit pieces), Sampletank 3 (23,000+ sound bank), many others. Effects (over 750): Waves; Horizon with 50+ others, Nomad; Studio III + Magma, IK; Amplitude 4 Deluxe + most collections, T-Racks-5 Deluxe, too many others to name.
Mixing, Mastering, & Production WiLLi & the MusicMachine