Amazon furusato issues

I did my furusato donations through Amazon this year and I've had some issues in registering my one-stop tax application online, with both the mypg.jp and furumado.jp sites. I have 5 donations in total, and all 5 of them give me a "donation not found" error when I try to register them.

I assumed, like with most Japanese web forms, it was an issue with the format of my name. I contacted each municipality account to update my previously stored name (from my Amazon account, in romaji) to my katakana name. However, this doesn't seem to have solved the issue for any of my donations even though they have all now registered my katakana name. I have double checked all of the form data but I get the same error.

I did all my furusato through Rakuten last year using the same websites and didn't have any issues, so it suggests that this is somehow an issue with the Amazon system?

I was wondering if anyone else has faced similar problems and if there is some other fix that I'm missing out on.

Thanks in advance!

by Best-Persimmon7860