You should be able to override the modeler plugins at the device level. One way to tell if a device has an override is to navigate to the device's modeler plugins window and see if the "Delete local copy" button at the bottom is active (black rather than grey). If you do override at the devoice, do ensure you use the Save button.
Cheers,
Jane

Email: jane.curry@skills-1st.co.uk    Web: https://www.skills-1st.co.uk

A modeling cycle has no way to assign modelers so I think something else must be going on here.

When you say modeler plugins get reassigned, can I just check that you really mean modeler plugins and not performance templates (which you will see at the bottom of the left-hand menu on a device's details page)

Is it possible to pastebin or email the screen showing modeler plugins for the offending device

Run the modeler in the foreground with debug set on to see what is going on. For a device fred.com, use:

zenmodeler run -v 10 -d fred.com > /tmp/fred 2>&1

and then inspect /tmp/fred

Cheers,
Jane

Email: jane.curry@skills-1st.co.uk    Web: https://www.skills-1st.co.uk