Her vote was provisional and removed on review:

"Ultimately, her vote didn’t even count. Provisional ballots are subject to review, which ultimately led to an investigation of Mason."

Why should criminals be denied representation? Does committing a crime suddenly make you no longer human?

Right, I can understand arguments for "you shouldn't lose the vote in that case", but that's a separate issue from "given that her vote wasn't valid, she was disenfranchising someone".

And "no franchise" does not imply "not human", unless you're saying that every country should allow foreigners to vote in their election or else they're deeming them non-human.

this seems to be devolving to word games. your use of the word "hurt" appears to be quite distinct from how "hurt" seemed to be used by the op.

It's not a word game; it's progressed into forcing the OP into clarifying why disenfranchisement can be such an atrocity but not "hurting" in any relevant sense, or (if I understand you) why all non-physical crimes should have some really low cap on punishment. Seems like progress to me, and unlike a word game.

Why is it "invalid" vote?

Setting aside whether or not the law is a good one (which is also worthy of discussion), in some jurisdictions people convicted of felonies are not allowed to vote. A vote cast by someone who is not allowed to is in that sense invalid.