Kaspersky anti-virus is causing this effect for many users. See https://support.mozilla.org/en-US/questions/1271866?page=2#answer-1266662

I see you also posted https://support.mozilla.org/en-US/questions/1272431

Bill, was Kaspersky the cause of your problem??

By manually re-downloading the plug-ins, I got them to work. So it seems. So, I would say KIS was not the the problem source. Thx.

Bill99 said

Have 68.2.2. Keep getting popup within TB saying that I need to download the latest when the latest is already installed?

Bill99 said

By manually re-downloading the plug-ins, I got them to work. So it seems. So, I would say KIS was not the the problem source. Thx.

I am confused. You have apparently solved some problem, but I have no idea what it was.

Guess I'm getting my problems confused. The "download latest" issue has gone away.