Deathstalker V2 Pro connects via high speed dongle and USB, but not working on bluetooth.

I can use the keyboard using the dongle and the wired usb connection. But when using bluetooth there is only blinking, and the keyboard won't work. Windows 11 says it is connected , but it just isn't working. Removing it doesn't help, updating software doesn't help. Tried all the “solutions” with regards to bluetooth connections.