I open a message in a tab (usually by double-clicking), it opens all right. I minimize Thunderbird, switch to a different application, then switch back to TB, look at that tab, and it’s showing a different message (usually a “close” one, e.g. some older one from the same thread, though not necessarily). It also happened when I opened several tabs in a row (to all of them).
It never happened to tabs that have been open for a long while (I have some months-old tabs there, persisting between updates), those are all right.
I’ve been seeing this with the latest betas of Thunderbird 66. Tried compacting the relevant folders, as well as repairing them, no change.
Today I’ve been running the current release (60.5.1), and it doesn’t exhibit this problem.
If there’s anything I can do help fix this, please tell.