While measuring a pdf the measurement no longer saves. Please help

I have used the measuring tool for marking and measuring areas and distances.  Very useful that the measurements save and I can leave notes with each one to be view later or by others.  All of a sudden the measurements no longer save.  Once a measurement is complete (distance, perimeter or area) it will disappear with the next click of the mouse, no matter where I click.  This doesnt let me make notes, it doesnt let me fine tune the measurement by moving the points etc.

I have looked through preferences, I have tried other pdf documents,  not sure what to do next.

Any assistance would be greatly appreciated.

Thanks in advance!

Ben