"Message Students Who..." Glitch?

Community Novice

I have an instructor who used the  "Message Students Who..." feature in Grades and she said the email was sent to every student in the class instead of just the students identified. 

I believe she chose the "Haven't submitted yet" option, which caused quite a frenzy since students who had already submitted received that message.

The instructor mentioned that the column the message was sent from was a Soomo column. Could this be the root of the issue? My first thought was that an issue occurred because the assignment column came from an external site, meaning Canvas couldn't really tell if the students had actually submitted or not, so it just messaged everyone. Anyone else experience this before?