Thanks for the info, good to know that it isn’t my machine that’s going crazy. Not the most disruptive bug, I recon - but distracting and confusing nonetheless.
Update on the general sync issues:
I have by now also managed to make the Project work on the SanDisk 32GB SDHC Extreme. I get stable sync via USB, and the reported main issue in this thread of Sync/playback issues seem to be resolved. Looks like it was the SD card I initially used after all.
All other bugs reported here have been moved to bug report 5911 for unwanted changes of other parameters accompanying modification of multimode envelopes A2-2 and A2-7 in this project, & 5932 for the SD card gibberish name and folders
5911: Modifying Multi-Mode envelopes causes changes in other, unrelated parameters (Filter, Pitch)