Was not able to solve this without a 3rd phone number. My son's Apple Watch (with cellular) was able to receive the verification code. Never got my primary number (I'm still told used too many times) nor my eSIM number ever worked.

Update: I was at 10 devices. I signed out of one, but nothing at all changed. I signed out of 2 more, and now my primary mobile number, when used to confirm a sandbox account, does NOT say: "Could not connect to iCloud - This phone number has been used too many times. Choose a different number." ...now it says... "Too Many Codes Sent - You have sent too many codes to this phone number. Please enter the last code you received, enter another phone number or try again later." (Of course I never received any codes at all. From either number.) It is then waiting for me to enter a code. (Regardless of which number I try.) I have no codes for either. I'll try again tomorrow.

I've reverted to Xcode 26.0.1 and is perfectly normal again. Wow that's not 5x faster is 10x faster at least. Definitely not MacOS since am still running MacOS 26.1 RC1.

I now have 26.0 Release Candidate (both Tahoe MacOS and Xcode) and it has addressed the issue for me... files are not merely being PROPOSED they ARE being CREATED. Yay.

I have no idea why some files can be created and others are just PROPOSALs. I asked ChatGPT (via Xcode) to create a slew of code, and after 5 files were created the rest were just proposals. They were all in the root of the project. They all looked the same to me.

I am also having this issue with Xcode 13.4.1 trying to import the XCDYouTubeKit package ( github / 0xced / XCDYouTubeKit ) from their Github repo. It looks like it is hanging on "Verifying XCDYouTubeKit" at zero progress-bar progress.