It asserts on an invalid 0 value of predictedDisplayTime. The OpenXR runtime is supposed to never return this value according to the spec. Seems like it could be either a bug in the runtime, or a bug in Unreal where it tries to use the value before getting it with xrWaitFrame().
To verify which it is, you would need to see if it runs xrWaitFrame() before asserting, and what value xrWaitFrame() returns for predictedDisplayTime.