Added the plugin and it worked great for the initial import. The next time it synced, though, some posts started getting unpublished and changed to drafts. Attempting a manual sync has changed them all to drafts despite the "Default Post Status" setting being set to "Published". I even attempted to change it to Drafts, saved, changed it back to Published, saved, and re-sync'd and now nothing that I do will revert them back to Published.
Additionally, while trying to fix this, I attempted to use the options to remove all synced posts but none of the buttons work on that page. Console shows "ReferenceError: Can't find variable: SubstackSyncProgress".