Xcode Accounts BitBucket Server Account Validation Failed

Hi All,
trying to add a new account in Xcode fails with above error message in red on the “Sign in to your BitBucket Server account” dialog:

"Account Validation Failed"

BitBucket Server 7.6.
Xcode 12.5
macOS 11.3.1

Please note the following:

• The Personal Access Token works as I use it to clone repositories on Terminal.

• Xcode accounts work otherwise as I can add a GitHub account.

• BitBucket Server is good as I can add an account to SourceTree, albeit using SSH rather than Https.

We have checked the BitBucket Server logs and nothing shows. Console logs for process - see text attachment - com.apple.dt.BitbucketServerHostBuiltInExtension show a connection error:

finished with error [-1003] Error Domain=NSURLErrorDomain Code=-1003 UserInfo={_kCFStreamErrorCodeKey=8, NSUnderlyingError=0x7fe874e223c0 {Error Domain=kCFErrorDomainCFNetwork Code=-1003 UserInfo={_kCFStreamErrorCodeKey=8, _kCFStreamErrorDomainKey=12}

-1003 is an error code for CFURLConnection and CFURLProtocol which indicates: kCFURLErrorCannotFindHost.

That is surprising given the host is reachable via other apps on my local machine.

Any ideas?

Thanks & Best Wishes