question about maths symbols in braille screen input

Hi all,
wondering if anyone knows the answer to this, I have now set my braille screen input to use UK braille instead of unified braille,
today I wanted to get a plus sign in a text message, but I couldn't get this to work in either contracted or 6 dot braille, to do my plus sign I did dot 5 and 6, then with no space I then pressed dots 1 and 2 with dot 5, a lower f basically.
anyway I didn't get my plus sign, I got a semicolon and an exclamation point, is there problem with braille screen input and maths symbols?
as an experiment I also tried to right an equals sign buy pressing dots 5 and 6 followed buy a lower g, but that didn't work either.
I can write numbers with no issue, and I can't believe these basic things aren't supported as a pound sign is supported unless of course the rules have changed since I did my braille? I suppose its possible I might be rusty as I haven't used it in years and I am only really using it when I am two lazy to reach for a Bluetooth keyboard.