I have built a scene with about 15 scatter objects and in total it is scattering about 30K objects. All works as expected so far.
I then either merge or paste the scene into another scene (I tried a few different scenes...same result) and some of the scatter objects (ones with a lower count) behave ...

Thanks for the tip jeremy.

I tried what you said and unless I am doing something wrong, I get the same missing texture error.

Any other ideas?

Many thanks

Use Globalized filenames, as these will be an absolute reference to your texture. You can select the textures via Window > Project Asset Inspector and then choose Asset > Globalize Filenames from the menu. Then, go to Octane Dialog > Materials > Octane Texture Manager and refresh the file list ...