update: thanks to @nils for helping me troubleshoot, we were able to confirm that the issue is being caused by a conflict between the PlatformIO extension and Workbench. it seems they released an update recently (September 10th) that likely introduced this issue. from what i’ve heard, prior versions worked fine alongside Particle Workbench.
short-term, the fix is to disable the PlatformIO extension and close + reopen VSCode.
i’ll try to diagnose the underlying problem and work with the PlatformIO and VSCode teams to get some sort of fix in place.
apologies for the bumps, thanks for you patience 