Michael.

I click to start the line and immediately begin typing on the numeric keypad and the numbers are displayed in the X,Y,Z box without me clicking on it.

If I click to start the line and then type: 4-7/8" the line is correct.
If I click to start the line and then type: 4 7/8" the line terminates somewhere near the Origin, in fact all lines show similar behaviour whe using the 'space' character.

Martin.