Dropdowns stopped working

I have a couple of dropdowns that were working fine during my last build, which was about a month ago. Now, when an option is selected from either, the field goes blank in the Preview (web and Android platforms tested) and the options list is gone.

Nothing was changed in the configuration that should have affected this. In fact, I rolled back in history to when it was last built and it’s still not working.

Could it be something in an updated preview or build routine?