Hey all, it seems like in logic 10.7.8 they fixed the issue (the sidechain signal was not properly PDC‘ed when feeding the sidechain of a compressor that is on an Aux/Bus in a sessions with latency-inducing plugins).
I‘ve tested it with Trackspacer, ProC2, ProMB, Logic onboard compressor. All kinds of scenarios: Empty session, Full session, latency-inducing plugins on aux/on tracks. Sidechain-Compression was tight in all scenarios.
Test System is: MacMini M2Pro, MacOS Ventura 13.3.1