KeymanDeveloper 14 "Unable to start debugging -- failed to switch to language with error 80004005"

My project compiles successfully, I get this message when trying to do several things:
a. “Test Keyboard” under the Keyboard Menu
b. For on-Screen, when I select “Fill from layout”

The language of the keyboard is “phk” (Tai Phake), using the Myanmar Script. The keyboard layout includes variation selector U+FE00 on some of the keys. It also has rules for reordering the code points. And it includes rules for deleting two code points when there’s a variation selector.

KM Developer version 14.0.282.0, just re-installed.

Any hints?

Can you share the keyboard project folder with me either here or in DM?

I’ve reproed and reported the issue here bug(developer): “Unable to start debugging – failed to switch to language with error 80004005” · Issue #5846 · keymanapp/keyman · GitHub. If the steps leading up to the error for you is different from that, please clarify what you have done prior to seeing the error.

Also, if you still the error, send us a diagnostic report from within Keyman for Windows under Support tab.

A workaround for now is to uninstall both Keyman for Windows and Keyman Developer, restart the machine and then reinstall them. Make sure that Keyman for Windows is installed before Keyman Developer. This works for me.

I had that problem some weeks ago. Uninstalling and reinstalling did not help.
What did help was associating the Debug Host keyboard with the En-US keyboard (avoiding the En-NR keyboard, which came up first when I looked for En).