Overridden PrepareProductOverviewModels inconsistent with plugins

I have overriden the standard PrepareProductOverviewModels call in a 4.0 plugin. This works fine and works as it should. However when the another plugin (Nop-Themes/7Spikes AjaxFilters, just for reference) calls the same PrepareProductOverviewModels it doesn't use the overriden version it runs the standard out of the box one but only in a live environment, in debug it works fine calling the correct override version.  
I am at a loss to understand why that would be the case.

Anyone got any ideas?

1. check your Order at dependency register. give highest order.
2. check warning from admin -> system -> warning

Order on my plugin is set to int.Max

public int Order => int.MaxValue

No warnings at all.

There won't be any warnings as it is not an error as such
Have you tried restarting the Webserver and Application Pool ?