Board Thread:New Features/@comment-46303893-20200716110931/@comment-168424-20200716211813

Okay, so I just repro'd your issue and it does seem like an oversight by the Visual Editor functionality... I would report it to FANDOM staff via "Contact us".

The legacy Visual Editor really should warn you when trying to navigate away, but it doesn't. If you want to avoid this problem, you should use the Source Editor. They may not want to fix the problem, though, since the Visual Editor in the UCP doesn't seem to have this problem.