Oculus UI flickering

After deploying our project to oculus store we were rejected because of UI flickering. The problem is we can not reproduce this bug on our device and we have not much ideas what could be source of the problem. Oculus log says it appears on thermo vision, but the only differences from normal mode are enabling post-processor grain effect and a purple colored plane.
If anyone faced same problem or have any ideas how to fix it - we would glad to hear all the ideas. Thanks.