Animation - Rail Clone Roof Tile - Random VrayMultiSubTex - suddenly changes half way through animation

[Grant XR3D]

. . . Sorry if this has already been covered, I searched for a bit and couldn't find anything. . .

I'm using LiveLink to animate a home. The home has roof tiles on it. The roof tiles were created with Rail Clone. I am using VrayMultiSubTex set to Random and By Render ID.
Half way through processing the tiles suddenly change as if someone changed the Seed number.
There is no ryme or reason as to the timing of this it just randomly happens every 50 to 100 frames.

I have checked to see if the Seed is animated and it is not.

Here is frame 129 and 130 for example.
Might be hard to see with single frames but it is a very noticable jump when played.

Thanks in advance!

[vladimir.nedev]

The "Random by Render ID" can indeed change, since it's just the internal identifier for the instance.
My guess is that the RailClone object gets updated for some reason and new render IDs get assigned to its instances.
Maybe the RailClone object depends on the camera (frustum options) ?
The same can happen in V-Ray as far as I know.

You can try using "Random by Particle ID" instead.

Greetings,
Vladimir Nedev

[Grant XR3D]

Worked like a charm, thanks Vlado.
As always I apprieciate that you and your team are always willing and available to help!!
Thanks
Grant