I have the same problem as @isa_imadoglu2, same steps and outcome when trying to enable a new capability. When I enable "Associated Domains" and click Save, I get a 501 error and the change doesn’t persist after refresh: Response: PATCH to http://developer.apple.com/services-account/v1/bundleIds/PBB2JSKG7Y not supported. Reference #8.5941602.1755400657.8a713a7 Then the changes don't persist on page refresh. I also tried creating a brand-new Identifier and see the same error.

I’m experiencing the same issue: a 501 error when trying to update any capability on an App ID. https://developer.apple.com/forums/thread/797201 So far, the only workaround I've found is to select the desired capabilities when creating the App ID, since the site makes a POST request instead of a PATCH. Unfortunately, this isn’t ideal for apps that are already published on the App Store 🥲