Numbers have disappeared on ruler

Hi,

normally when we snap two conveyors on each other with the connector ports in Plant Layout Engineer and you want to have for example a distance of 100 mm between the two conveyors, you can drag the robot a bit and we are used to double click on the number (distance) to give it an exact distance.

So in the image below I would click on the distance 119.94mm and change it into 100mm

However, on one of the PC's the ruler appears, but the numbers are not shown anymore since a week. (So, it does show the ruler, but doesn't show 0, 119.94mm and 510)

Has anyone any idea why this happens?
Is it a setting? Or maybe a bug (it only happens on 1 PC and it used to work fine)

Thanks for your input.

Marcel