Recently transferred a domain from wix and the custom name servers are stuck on wix. I get the error below when I try to update. It's been 3 days and no response from support. 

• Update nameservers

• Using custom nameservers is an advanced setting. Entering the wrong nameservers will disrupt existing configurations with your website, email, and more.

• We were not able to add the nameservers. Try again and, if the problem persists, contact Customer Support.

We are having the same issues and no help from Squrespace. I have been trying to solve this all day. Chat and email. Nothing. 

Submit the ticket and wait. Took 3 days for me. This was their response. 

"Thanks for contacting us about this. We noted your report with our Engineering and Design teams for review. They’ll use this feedback when creating fixes and improvements for future releases.
 
With that said, I can see that this was due to a syncing issue that occurred after your domain transferred in. I’ve taken action to resolve this issue and you can now make any changes to your custom nameservers going forward if you would like."