I have tried using Tools->Convert Font->Convert to Symbol Font, with glyphs mapped to character codes in the range 0xF000 to 0xF0FF. Specifically, codes 0xF021 to 0xF054, which I believe should be fine as this is the range the font started with. I have also tried the range 0x21 to 0x54 just in case, which didn't work.
The FontCreator version is 126.96.36.1999, 64-bit.
Some additional info:
- Every time I close and reopen the FontCreator project, it seems to get reverted to a Unicode font, which is strange.
- I believe this font has been successfully edited with a previous version of FontCreator (not by me though).
- I'm using Windows 10 Pro, version 1809, 64-bit.