‘Increase Text’ bug

I added the increase and decrease font size buttons to my format toolbar but when I selected an existing word (currently at size 11 or so) and press the ‘increase’ button, the text was changed to size 2 rather than increasing by one.

It also seems to go from size 10 to 12 missing out 11. Hang on, just tried it again and now it’s jumping from 11 to 13 missing out 12. Something’s odd here :confused: