FlipFluids & Ocean modifier as displacement. Baked frames in 3D view show all movements but rendered animation not. Manual keyframe ok. Any solution? I have created a FlipFluids simulation in Blender 2.81 ( 2019-11-25 21:45) and added an Ocean modifier in displacement mode to the fluid_surface.
Then I have baked the complete sim from within FlipFluids.

When I move from keyframe to keyframe in the default timeline everything is moving as desired in the default 3D window:

Ocean modifier waves, FlipFluids waves &amp; wake, flags, radars...

When I render the complete animation everything EXCEPT the ocean modifier waves are moving. 
The ocean modifier waves remain static but the FLIPFLUIDS waves move on that surface.

I like to add that ALL modifiers and elements ARE enabled for renderings.
D-NOISE: AI Denoiser is on (switching denoiser off did not help). I run a Win 10 Pro, HP Z800 with dual Xeons, 72 GB of vRAM and a GTX 1060

If I render &amp; save the frames manually individually by hand the ocean surface moves! But thats not something I really like to have to do on several hundred frames

As its working when rendering&amp;saving each frame manually as image (Png) and its not giving the same result when saving out the same images (Png) when I hit render animation, I do suppose this might be a bug in 2.81.

Does anyone have an idea how to fix this, preferably without rebaking?
Turned out to be a bug in Blender 2.81.
The team of Blender will be fixing it:

https://developer.blender.org/T71908