Hi Steve,
As usual, I try to never answer from memory, so the suggestion the manual does with the Random effector doesn’t work here, I tried it with a 91 image set up:
https://help.maxon.net/us/#OERANDOMIZE-ID_MG_BASEEFFECTOR_GROUPEFFECTOR
You might get different results. I have to test this more, it worked in the past.
Anyway, why the Random Effector? Each clone has normally its own ID, except for the Grid Array.
I would just go with The MultiShader, load them all at once and have it set to Cloner ID (Index ratio.)
Here is an example, I used the Matrix to get the position and the Cloner to get the ID.
Scene file
https://www.amazon.com/clouddrive/share/pvXtMGITJMi7BJuiB5m9uU534INj1nGjxzDQgHdfFx
If you take a look into the Multi-Shader, you can easily move images up and down, to change the sorting.
This might not be what you are looking for, so please (as usual) share a simple set up with no 3rd party stuff in it, thanks. I might can share a solution, fingers crossed.
All the best