Getting Terrible Frame-Freezes... but game is still being Update()'d

Hey Unity Devs, I’m hoping that someone can help me shed some light on a crazy bug that some of our Android players are reporting.

TL;DR: Bad 1sec+ frame freezes, but game keeps updating. Is this a Unity Rendering Bug???

The long version:

We get 1+ second frame freezes whenever coins are added to the players total. BUT the game keeps updating in the background. Here’s a video a user sent us showing the HUGE lag spikes:

- YouTube (After the lag spike - the trains have continued moving, making the game unplayable)

After spending several days trying everythign I can to fix the problem (I can’t actually reproduce it on any device we have access to). I wrote some code that would make the problem WORSE… so here’s what it looks like when we actually have bad code that sticks on a frame.

- YouTube (Notice that the trains don’t continue moving behind the lag.)

This is currently happening to maybe 1% of our players, and I can’t (yet) see any common ground on device type, or OS version.

What can cause rendering to stop while we still get calls to ‘Update()’ ???

More Information from one of our players. I’ve highlighted the important bits.

“I tried the Open GL and the first two
plays Mons and Bruges were perfect. I
had two perfect balloon rounds which I
think is a first. One in Mons and then
one in Bruges before the (video)
freezing returned on my third balloon
when I played Amsterdam.”

game continues I can hear it and even
control the trains
. Only the video is
frozen for a short, random amount of
time. "

We sent them 2 builds, one that disabled multi-threaded rendering. No change. And one that used OpenGLES3.0 (previously we just used gles2.0). In the OpenGLES3 build the problem seemed to go away for a little while. But then came back.

More videos showing the issue:

I can’t recreate the problem on any devices that we have access to. At this point I think it’s maybe the Unity UI system?