Required Rule does not make the red asterisk show next to the field
This cane happen when the expression is written in such a way the client-side rules are not able to evaluate it. One example is a Date/time driven expression such as $(CreatedDateTime >= "05/03/2018"). This expression will be enforced upon save, but it causes some trouble in the client-side browser logic so the red asterisk marker does not display as desired.
Solution / Workaround:
Adapting the Date/time logic to use a different expression and a function to translate the date/time math into a numerical value will make the asterisk render appropriately.
One example of how to do this is as follows:
$(DateDiff("minute", CreatedDateTime, "5/3/2018 12:00:00 AM") > 1)