Hi, probably a bit late for you now as your post was in the beginning of April, but here is my recent post on the shipping label problem I had. Didn't get resolved so I just paid for post at the PO counter.
https://community.ebay.com.au/t5/Technical-Issues/Shipping-label-error-message-Something-went-wrong-...
I only have a few listings and not sure if it will still fail on me with the next items sold. Probably just pay at the counter again as have to drop it at the PO anyway...
The next thing is the new seller hub that has been thrust on me today...sheeez. Managed Payments next no doubt.
Cheers...and good luck ๐
