If both User and Node mentions are enabled with the same marker the node search doesn't work

Problem/Motivation

I have a brand new site with one user and one node of content. If I only have the node mentions enabled for my text format I can find the node but as soon as I also enable user mentions I can no longer find the node. This is the case if the marker is the same character for both: in my case I was using @. This seems like a bug. Either the search needs to be able to search both types of entities using the same marker or there needs to be form validation for the text format telling the site builder the markers cannot be the same.