I see that it is nearly 4 years since this issue was raised and it still hasn't been fixed. I've tried inserting a non-breaking space using the Windows Character Map, the Alt+0160 keypad trick and copy and paste from a Word document with a non-breaking space. In all cases, Rise replaces it with a normal space. All you have to do to fix it is to stop Rise from messing about with a valid character. If anything, it should change it to an html
This is an essential feature in lots of text. I need it to insert non-breaking spaces between a number and its units, e.g. 150 m or 60 km/h. It looks really messy when the units wrap onto the next line.