Field Validation causes Freeze

[alta_flyer]

I have a field which has validation selected to only known values from a value list (populated from a separate field{Names} )

When I enter an invalid value or leave it blank, I get the alert dialog box from the field definition but then the program freezes and I cannot proceed.

Valid values seem to work fine.

[alta_flyer]

I am using FMP 18 Advanced and Windows 8.1.

Client on Windows 10 does not seem to have the problem

[Fitch]

Double-check the 8.1 updates?

Windows 8.1 Standard Edition
Windows 8.1 Pro Edition
System updates 2919355 and 2999226