I had sent an inquiry to support about this before Jason posted, and it was suggested there that we swap in ADS version 3839 (both DLL files), which seems to have restored the sync functionality. Thanks for your help.

I'm not 100% sure about which ADS was in place before(don't have remote access and Jason does his own upgrades), it's likely it was whatever came with either SalesAnalysis 9.3A 2020-01-28 or one of the Sysupdaters as those should be the newest recently installed releases, according to our notes.