Other Mail folders missing in Thunderbird

I opened TB on my office PC yesterday and noticed something very different about it; all of my inbox folders were missing. I initially panicked and thought I'd lost 4 years worth of saved emails (the ones in folders are the important ones!) but I checked the account on my iPad and thankfully the folders and messages are all still there, so it's a sync problem in Thunderbird.

To check if this was an isolated issue, I fired up TB my laptop with no Internet connection, noting that all the folders were present, then connected it to the network and restarted Thunderbird. As soon as I did that, the folders disappeared. I have tried all the sensible things like starting the client in safe mode, with no add-ons, updating it, checking folder view settings etc. Nothing has worked so far, does anyone have any idea what I could try next?

 

Never mind, I found the fix for it myself with some calm, logical thinking and much hunting through Thunderbird settings!

The "show only subscribed folders"checkbox had been marked, probably during an update, and needed to be unchecked under Tools > Account Settings > Server Settings > Advanced.