I've been having some weird issues with the dropdown not appearing on some of the Windows 8 computers. It always works on the two Mac computers. These fields have been used for 3 years without issues, nothing has changed on the layout. Sometimes just closing Filemaker and re-open the database will solve the problem, sometimes rebooting Windows will solve the problem. Sometimes it will work for several hours then stop showing the dropdown calendar. All the windows computers are rebooted nightly and not every Windows 8 computer has the issue. Its sounds like to me that a Windows Update has happened and there might be some conflict with Filemaker.
Windows 8.1 (64-bit OS)
FileMaker Pro 14.0.4 (32-bit)
Mac Server 10.10.5 - Filemaker Server 18.104.22.1682
I always look for "what has changed" for troubleshooting. I've been testing some filtering speeds and in a table I've creating 500,000 test records. However this table isn't a table that the dropdown calendar or dropdown list is connected too, those fields are in a different table. Also there doesn't appear to be any slow-downs with all those test records, the end users aren't aware of my testing.
I've included a video to give you an idea, the 1st part is the calendar not showing and the 2nd part is the dropdown list not showing. The user can manually type in the date and value so its a workaround for now. But its still strange behavior.