After updating the Mac OS X Server 10.10.5 version of FileMaker Server to 14.0v4 there was a problem when pre 14.0v4 versions of FileMaker Pro or Pro Advanced were running a script where a script invoked in another not-yet-open database would fail to set a value into a variable.
The database is hosted over a WAN connection. There is a Menu database that is opened directly and its OnFirstWindowOpen script calls a script in another database to check if the AccountName of the user matches a record in that database. The script in the other database goes to a layout and searches for the account and the sets a value into a local variable and returns that variable to the calling script. If the variable is empty the user is denied.
The script runs and the user record is found and the value is placed into the variable $ListingName but that variable does not get the value. I verified this by doing a Show Custom Dialog with the found count (1), the value of the field and the value of the variable which is empty. See attached screen-shots.