What exactly would Waukesha “holding back” precincts accomplish? The votes are in. Are you suggesting that people manufacture votes in Waukesha to counter anything done in Dane? The reality is, precincts with more people take longer to report, hence the reason that Waukesha hasn’t reported some of the bigger areas yet. Same with Dane. The totals that are in from Dane now are not from Madison proper.
Likely means fraud - just my bet. Dems are so dirty they always generate whatever they need in the way of votes, cast long before the election in some back room - then dumped into a friendly vote counting center on election eve.