CrossAccount sign in Hello Ross,
If i understood your question correctly you are referring to AWS Cross-Account Bucket Access, this is in fact a quite interesting question which we need to see from the software's side, so if you don't mind just send us the logs by navigating to Tools - Diagnostic, this will create a support ticket and generate all the info we need to check it from our side. Please reference this forum post in the description or mention Sergey N. Thank you.