Approval Process not triggering for specific user

Approval Process not triggering for specific user

Hi there! 

I have a simple approval process set up and have confirmed that it is working for at least one of my team (I'm super admin).

So, the process is set up correctly.

However, for a specific user in my organization, the process doesn't trigger when she enters in information into the trigger field. (Field is triggered when NOT EMPTY)

This is obviously very confusing, and I've already run through all the troubleshooting I can think of.

Has anyone encountered this issue?