Pokemon fused when being promoted

I had used two metal saucers to power up my benched Dialga Vstar. I then used a Scoop Up net to pick up my active Mew and when I selected Dialga Vstar to become my new active, both Dialga Vstar and Radiant Greninja jumped on top of each other into the active spot. See pictures below, at that point I was able to select both Pokemon but I was unable to use any of the attacks on Dialga Vstar that I had selected to be promoted into the active spot. On my next turn, I tried to retreat Radiant Greninja into the Dialga Vstar but I was unable to.

My opponent and I passed back and forth until they conceded. I seemed to be able to play the game normally, except that it appeared that my Dialga Vstar with 5 energies disappeared from play.

[Edited by Mod_Ice): Please be aware that posting images on the forum is not allowed.