Hi, my friend is having this issue, throughout troubleshooting the difference between our Xbox’s we found the following:
My Xbox is on OS version: 10.0.26100.4026
His Xbox is on OS version: 10.0.26100.4020
He has his Xbox on my home network using Ethernet so the only variable we were able to find was this difference in OS version.
We tried downloading the latest OSU1 file from the Microsoft website however this appears to still be the OS version ending in 4020.
I believe my Xbox on OS version ending in 4026 is on a preview build and therefore that’s why we can’t find an offline build to download to my friends Xbox.
I have no issues whatsoever on my Xbox and his account works alongside mine.
However on his Xbox both our accounts don’t work so it’s defo an Xbox issue.