Keyboard Mapping Issue with Hash (#) key

I have a problem with a UK-British USB keyboard on an RDP.  The Hash (#) key (Not the pound key (£)) works on maxOS 10.15.4.  However under Jump-RDP this maps to a backslash (/).  I press Hash and get Backslash.

Therefore I added a mapping from Hash to Hash: 

This now gives hash, great!! 

However the tilde button (~) maps through to pipe (|) also in error.

Therefore I map tilde to tilde:

But this very odd.  Every time I now press Hash, I get a Hash and a Tilde in my RDP:

"###" => "#~#~#~"

Where as the actual tilde button still shows a backslash.

I believe this may be a bug?

Regards,

Ben