Dead key dead at start-up. Then turns on. Why?

I originally posted this on the Hardware and Devices Forum, but perhaps that was the wrong place.
At any rate, no one responded.

Windows 10 version 1909

The problem appeared about three months ago. My keyboard layout is for the Icelandic language. It includes a dead key for vowels: á, é, í, ó, ú, and ý. So, I can type a or á, etc., if the dead key works.

I use the Microsoft Designer Bluetooth Keyboard. The dead-key vowels first appeared normally. Right at startup.

Now, just after start-up the keyboard will not produce the dead-key vowels. Then, from 15 to 30 minutes later, the dead-key vowels start appearing normally. I tried uninstalling and reinstalling the drivers, but no change.

Pressing the shortcut keys for the Icelandic language does no good.

How can I restore its full functioning from start-up?

Caledon Ken said:

Do you have a couple of input languages setup in settings > time and language. If so is Icelandic set as default?

No, the only input language is Icelandic.

AndreTen said:

List of startup programs (Task View / Startup) would be helpful.

These plus Dragon NaturallySpeaking.

Hope this helps.

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Caledon Ken said:

Have you tried removing power from keyboard, let it sit for five minutes and re-install batteries. Hoping this has batteries.

Yes, I tried this just before seeing this reply from you.

Caledon Ken said:

Have you tried removing power from keyboard, let it sit for five minutes and re-install batteries. Hoping this has batteries.

Yes, it is battery-powered. I tried removing the batteries, let everything sit on the desk at least five minutes (probably longer), and restarted. It made no difference.

AndreTen said:

i guess, at least both hotkeys apps can affect keyboard (dragon, and Dictation box). Are both running?
Stop one by one and check your kb

Thanks for this suggestion AndreTen. It's a partial Bingo. I removed all start-up programs and did a series of restarts, adding each in turn one by one. Only one of them was causing the dead-key problem.That's the good news. The bad news is the culprit. It is a very useful utility for me. I'll contact its creator. Maybe the fix is simple.So, a big thank you.