This is driving me crazy and has never been an issue until recently.
I’m running version 8.5.15 and working on a number of projects. When using some VST instruments they appear to work as normal but, for no obvious reason, after some minutes they go out of tune. It seems to consistently go sharp by nearly a semitone.
Halion SE seems to be the main culprit and I have a project which features a sequence of long single notes which demonstrates this. If I close the project and re-open it the issue is temporarily resolved. I have resorted to having to reload and then freeze the track. Audio tracks seem unaffected.
Any ideas? I have not upgraded drivers etc. Currently running i7 with 32Gb RAM and no CPU spikes. Audio interface is FW Presonus 16.0.2.