I am currently looking at a linear mixed model of with the formula `x ~ y * z`

I'm struggling with simplifying the model.

* When I run an ANOVA of my model it said there was no interaction so I reduced the model to remove the interaction term.
* However when I simplify my model I find my $R^2$ value drops and the significance values change (e.g., stuff becomes significant that isn't significant in my full model). To add to my confusion there actually is an interaction between one of my z categories and one of my y values! Despite this, my AICc value states that the reduced model is better...!

I've been made aware of the issues in model simplification giving false effects and was wondering if it's best to just keep my full model?