We need to wait for shaders to compile before starting a level sequence capture. POssible other scenarios where this may be needed are:
When levels are streamed in
When content is made visible for the first time while the sequence is playing
Change a global shader
Render out a level sequence without compiling those shaders
Result: Movie is rendered out with uncompiled shaders
Expected: Movie is rendered out with compiled shaders
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-46415 in the post.