So.….I have a machining that's made from a casting.
I copied the casting page of the drawing to make another sheet on the dwg to create a hog-out version (not from casting). All but 10 dimensions from the final assembly (casting part in an assembly with machining functions completed) are contained on the casting dwg.
I replaced the model on the views of the copied sheet and SW broke all the dag-gone dimensions!
What good is it to have this feature if it's going to break all the dims? It's the same part dimensionally with the exception of the machining ops.
Grrr. Sometimes I will never understand the rationale of SW devs.
Without sharing your files we can only speculate and ask questions.
When you replaced the model was it with a different, but similar (nearly identical) part?
Dimensions and mates all refer to the particular identifiers of the entities they refer to. If you and I were to both model a part that ended up geometrically identical, the surface identifiers would be different. As a result, if one is substituted for the other then mates would fail and dimensions would become dangling, at best.