Hi!
After some recent patch the edge emission behavior seems to have changed. This particle system used to only emit particles along the outer edge of the mesh and not from the diagonal. The Quad used is the standard Unity quad and does not exist as an asset in my project.
I’m currently using 5.5.0p3
Best regards
change to box - edge (z0) ; but this seems to be the new behavior (currently)
For meshes, we have always treated the mesh as triangles, so I’m not sure how it could have been different in an earlier version.
However, if you can prove it and submit a bug, we will of course look into it for you 
Also, 5.5 adds a new edge mode to the Box shape, which may give you what you want here.
Hi Richard, thanks for your reply! This is a screenshot from my phone with the current release version of the game. It was compiled with Unity 5.4. So I do think something has changed.
I’ll try the Box shape when I get home, hopefully that fixes it. Thanks again.
Interesting! If you’re happy to report a bug with a small repro project, we will find out why it’s changed!