The following steps solved it for me:
Go to the App Store Connect and select the team you don't have access to in Xcode.
Go to the "Users and Access".
Find yourself and click/tap your own name/user.
Change the "Preferred Currency" to anything else (and back, if desired).
Press "Save".
Logout/Login into Xcode and you should be able to see the team now in the list.
Post
Replies
Boosts
Views
Activity
Another case I came across is the usage of String variables in struct, when replaced with class this issue is no longer present. But these changes are quite undesired, but suffice while we wait for the problem to be resolved.
The issue is still present on Xcode 12 beta 3.
A (workaround) solution for certain cases of the problem could be resolved by replace any usage of the #.split with #.components on a String.
https://developer.apple.com/documentation/swift/string/2894564-split
https://developer.apple.com/documentation/foundation/nsstring/1413214-components