The game still disconnects in Ember Army for no apparent reason, past about Wave 14 or 15 or so, for me.
Once I reach Wave 14 or 15, it is a crap shoot as to whether I will be disconnected or not. Sometimes it will disconnect me on both runs, sometimes one, sometimes not at all.
I've had this problem on three different devices from three different makers. One is an Asus TF700T, one is a Samsung Nook, and one is a Moto GS5+.
It's not a connection issue as this only ever seems to happen in Ember Army, after Wave 14 or so.
It's not a device issue, because it happens on three different devices from three different makers.
It's not a hardware issue, because again it happens on three different devices... one of which is relatively new and not suffering from running older hardware (it runs on FFx4 no problems, without need for Min. Req.).
It doesn't appear to be a visual effects lag issue, as far as I can tell, because using the Min. Req. option doesn't help, either. I've had the problem with it on and with it off.
I don't have a screenshot, but only because there isn't much to screen shot with this. It hits Wave 14 or so, then just pops up the "you have been disconnected" message. No glitching that I can see, no weirdness, just one second it seems fine, the next I've been disconnected and my run ruined.
It appears to maybe be base related or Hero related, since changing one or the other can seemingly make it stop doing this for a while, but that could just be the semi-randomness of this bug.
I can't exactly experiment with this too much if I want anything resembling a half-decent score... not that I'm getting much of one, anyway. Still, I've tried to narrow it down as much as possible.