0
Windows 10 with most recent updates. This bug only started a few weeks ago after a major Windows update.
I have two keyboards setup on my user account that I use frequently. If I ever leave the computer locked and someone else logs in, when I get back to my account the input indicator is missing. The only way to get it back is to add a new keyboard to my user account - then I get all 3 keyboards to show up on the input indicator.
Logging off the other account completely does not help. Restarting the computer does not help.