I'm seeing failures & hanging replicating into Motherduck on the latest sling version with pro (smells like somethign concurrency related?). Looks like failures around flushing the temp table to the destination table & subsequent hangs. Haven't had a chance to pull debug logs yet but maybe tomorrow. Downgrading from 1.5.6 to 1.4.13 does the trick it seems.

Oh man, long leap. Yes, share logs and replication when you're able.