I have a solution based off the Time Logging starter solution. I have adjusted it muchly, though...
I have one layout with 3 different drop down calendar objects on them. Periodically these widgets will stop showing the calendar. You can click into the field and type things, but you can't pick a date. If I close and restart FileMaker (the whole thing, just reopening the file doesn't work) the functionality is restored...until some later point when it stops working again.
There is no Hide condition on the widgets.
Someone had mentioned a possible memory leak in another thread; I'm not certain where the line is, but I have seen this issue happen when the memory footprint is 400+MB in size. I can't say that it always happens at that point, or that it sometimes works past that point, just that when I notice it, that's what the footprint is. I often have multiple files and windows open, script workspaces, etc, so a footprint that size perhaps isn't unheard of. I tried watching it after just opening the file and the footprint was still small, but it didn't fail...and then I had to get work done.
OS X 10.9.5
file is opened locally