It appears this has been an issue since SW2011 I'm using SW2016, it just stopped working yesterday in assemblies.
I can get it to work if i spend a ridiculous amount of time to make a simple measurement between parts.
Work around is to start the tool, Right click, select "SELECT", click on surface/ edge/ whatever, hold control and select other object, Then click on the measuring tool dialog box.
Insane! I use this tool as much as zoom or rotate every day. What is going on??? I need it to work yesterday, when it stopped!!
Need a real fix ASAP!!! and reinstalling SW is absurd, it's only been running on this system for 4 mo.