Synthesis Footprint MTX lingers permanently in Absence of Mercy and Empathy

Here is what happened, I am using two skills that are Blink Arrow and Mirror Arrow. Something happens in this area that causes the footprints to permanently linger long after my clones are gone.

This screenshot is taken after being AFK for 5 minutes. They disappear when re-entering instance ( As I had to do as they had hidden DoT pools :D )

I am suspecting it's something to do with the Maven boss fight and Mirror and Blink arrow gems as this has not happened anywhere else.