This is expected behaviour following a recent update.

Spectating (the Watch button) is now limited to:

- Subscribed accounts, or
- Accounts with at least one dot dice (Oldtimer status)

If your account does not meet one of these criteria, the watch option will be disabled.

More information about Oldtimer scores can be found here - 

https://www.flyordie.com/forum/255217

This is a feature change, not a bug or account issue.