Can't switch between keyboard layouts using Alt+Shift+Number while focus is in text fields and some applications

Question

I'm running Windows 10, build 1803, and have set up my language like this:

with three input languages - US English, Bulgarian and Japanese. Each has an assigned shortcut - Left Alt+Shift+1 for ENG, Left Alt+Shift+2 for BGR, and Left Alt+Shift+3 for JPN.

Pressing the shortcut for BGR does not work in

• Firefox's address bar
• Microsoft Edge's address bar
• Chrome's address bar
• Notepad
• Web page text entry fields (like this one, in Firefox)

but it does work in

• Discord
• Skype

After a short while, the shortcuts for ENG and BGR get unset and Windows beeps at me when I press them.

This is a fresh Windows install.

What could be causing this?

Edit: After a bit more testing, if I don't bind a shortcut to the JPN layout, switching also works in Vim 8.1, but it still doesn't work in Notepad or the browsers.

Answer 1

I've given up on trying to fix this and have switched to using the following AutoHotkey script that lets me switch layouts with win+space. This solves my original problem which was that alt+shift and ctrl+shift are used in certain software so they're not convenient for use by themselves.

#Space::
PostMessage 0x50, 0, 0,, A
return