Can't change nameservers of a Squarespace domain

My website: rasyonelbicak.com was up and running last week. Then I decided to transfer my domain to Squarespace. 

After the transfer's completion, my website went down. Then I took my hosting provider's NS's and put them into the SquareSpace domain on 14.09.2024 it's been 2 days but the new NS's are not propogated yet. 

My hosting provider told me to trigger another propogation by deleting the NS's and readd them. Unfortunately I can't do this due to an error. Please see the attached file for the error. 

I was thinking about transferring all my domains to SquareSpace but if I will have this kind of problems, then this option is off the table for sure. 

Your Squarespace domain nameservers look to be correct. You are missing the proper A records. I suggest you go to your domain management panel and load the Squarespace defaults. You might need to choose "connect website using a domain I own" to do this. 

I'm having the same problem on my domain flourishingcapital.io and have no idea how to fix it.  It was previously working and out of nowhere broke on its own.