I am experiencing this very same issue. It was working fine with version 15470. Upgraded to 15575 and noticed the issue. I was crazy thinking my keyboard was broken but then I tested the keys with other emulators and it is working fine hopefully.
Something wrong happened in recent updates to emu which broke this hotkey.
Edit: it is a known issue and has been reported here: https://bugs.dolphin-emu.org/issues/12744 and it seems to have been fixed here: https://github.com/dolphin-emu/dolphin/pull/10248 , but I can't find a development build with this description yet in the downloads page.
Something wrong happened in recent updates to emu which broke this hotkey.
Edit: it is a known issue and has been reported here: https://bugs.dolphin-emu.org/issues/12744 and it seems to have been fixed here: https://github.com/dolphin-emu/dolphin/pull/10248 , but I can't find a development build with this description yet in the downloads page.