Was able to build the Synchronization-Fix tag on my system (with shared libs, had to specify LIBS="-lcap -lcrypto -llzma -lseccomp" with Actinium to build with shared Tor), tested, and it works fine after a sync from network. However any use of reindex will cause it to fail again, or fail initially if specified. I am up and running at the moment, but anything that could cause reindexing (daemon crash or unexpected stop, unexpected system reboot, etc) will trigger this again.

Thanks for looking into this.

EDIT: spoke too soon, after a while it crashed with the same error again, with no corresponding debug entries - just connection logs.