Issues transferring domains to Cloudflare

Any help greatly appreciated. I’m trying to transfer a domain to CF. It’s already on CF in DNS and has been running for a year. It’s currently with NameCheap and I have unlocked it and removed the WHOIS lock ready for the transfer. I also have about 40 other domains on CF. All I get when trying to do the transfer is:

I do get this error whilst trying to view the above page:

API Request Failed: POST /api/v4/accounts/xxxx/registrar/domains (504)

where xxxx is a long string of numbers that I assume are unique to my account.

I have exactly the same problem with no domain showing up for transfer (there should be at least two).

Additionally, there is no domainunder “Already on Cloudflare” (even though there should be one).

Anyone knows how to fix it?

It suddenly started working for me today - hopefully works for you too.