I'm running version 14.3.4. I think this may have happened after my last update.
When receiving emails, I normally flag emails that I need to respond to at a later date. I simply click on the flag to the right of the email and it toggles to a red flag. When I have completed my task, I click on the red flag and turn it into a green check mark, indicating to me that I have completed my task. I have flags that may be months old but still important to me.
Since yesterday, all of my flags are lost. I tried flagging emails but within minutes, the flags all toggle off.

why is this happening?