This is apparently an issue Weebly is aware of (you brought it to their attention) and hasn't yet fixed on their end. And just like you, I'm struggling getting any kind of support.
I'm having the exact same problem (the first part, at least)...I purchased a domain name to assign to an existing weebly site I own (I own a Pro subscription). I want to forward it to my existing domain. I went through all the steps to make that happen, and click on 'save' in the top corner, and it's now just 'saving...' (like you said, for hours).
They sent me an email to confirm my identity, and I confirmed it. I have sent in two requests on line for help, have posted here in the community...and am still waiting. I can't find any other way to contact them. Based on your post and their reply, it's a problem that they know how to fix.
