Smart Switch not working

[Audiophobe]

Just got a Tab S6.
I've had a Tab S3 for years and have been very happy but it's gotten a bit sluggish so decided to treat myself.
I set up Smart Switch on both sides and it sets up successfully but then the S6 says I have to delete 5+gb on the S3, not the S6, which made no sense to me. But I tried anyway deleting pics, documents, and apps but didn't even get half that.
I contacted Samsung Support and they truly were useless (which surprised me since I've been very happy with Sam Supp over many years).
I'll try them again but any ideas?
Happy New Year to all!

 

[SpookDroid]

Have you tried doing it by parts? (Moving apps first, then pictures/media/documents, etc.?) If the S3 is full, it might be creating back up files there before transferring to the S6 (not sure how Smart Switch works in that regards, tbh).