Hi Ryan,
Materials do not have an auto invalidation system based on the state of their content: if anything a material depends on changes and would require the material to re-translate, this needs to be done manually by opening and resaving the material.
If the change you make are code-related, for instance because you’re changing how a UMaterialExpression is built, or you make a change to the translator, you need to bump the material DDC key. Look for ‘MaterialTranslationDDCVersion’ and bump it to a different GUID. This will cause all materials to be invalidated and retranslated/compiled.
I hope this helps.
-Massimo