They are aware of the issue, this is from the Technical Support forum:-
Greetings,
It seems that the keyboard layout for hotkeys was changed to English with patch 9.2, so if you have another language selected for your keyboard some hotkeys will not be recognized. Your language layout should work normally in chat, only hotkeys are affected. We are investigating this at the moment and it should be fixed soon.
Background software for keyboards, addons and settings in WoW do not appear to be responsible for this. The only temporary workaround is to open the keybindings in WoW and set the same key you used before again as Key 2. This will allow you to use the same hotkeys as before and can be reverted once the issue is resolved.
Source:-