What does the activity for that episode in Sonarr show?
Are all the releases from the same indexer?
Based on the errors in SAB the sizes are all different, which is one of the pieces of information that Sonarr uses to determine if the release is blacklisted (Release name, size, release time and indexer are all used in various ways).
If Sonarr sends a NZB to SAB and it fails Sonarr will blacklist it and search for another release (depending on setting) or wait for it on RSS, since there are new releases RSS will pick it up rather quickly.
Have you set a minimum age for releases to be before Sonarr grabs them (Indexer settings)? If not try setting it to 20 minutes or longer and see if this issue persists, I suspect its propagation that is causing the failures and waiting longer would help.
Previously there was a bug that prevented Sonarr from re-grabbing a release from RSS when it failed and that quality was already grabbed, which would expose this scenario.