I'm in the exact same boat. 

Something unexpected happened every time. 4 different devices MAC and Windows, 4 different browsers and it does exactly the same thing. Cache and cookies cleared, incognito mode, private browser which is compounded by the AWFUL support guy who was reading his script instead of someone knowing what to do. 

24/25 tax year transactions disappeared and a new bank connection shows none after the guy rest the account so I have lost all of the work i did.

8 hours trying to sort it including the support team and ended up just cancelling the subscription as QBSE is useless. Shame as it was my go to so now I have to start 24/25 all over due to QBSE and it's terrible support. Truly awful.