If you go into Windows Explorer in that directory and view details, does it say that the key file is of type “Text Document”? If so, then Windows Explorer is hiding file extensions for known file types, and the file is REALLY named 47225-BOMB.key.txt…which won’t work.
You’ll need to turn off that option on the folder so you can rename the file, removing the .txt extension, or go to a command prompt and do it from there.
That’s the most likely possibility, anyway. I’m about to fall over sideways and sleep…it’s laaaaaate here. Do let me know how that turns out and I’ll have a look in the morning if that didn’t do it.