I was encouraged to share this information on the forum since it could affect other stores as well. Apparently the most recent update pushed for WER has a bug where the tiebreakers are calculated in the incorrect order, looking at a player's GW% before Opponents' MW%. Wizards is aware of this bug and sent an email to affected stores asking them to roll back to the previous version. However, not all stores were sent that email who should have been (as confirmed by the support rep). The only other relevant piece from this is that the normal link to download WER is currently disabled (to prevent more stores downloading the bugged version), so if a store is looking for it they'll need to find another source for now. Hope this helps if anyone else notices a similar issue! We were able to roll back to a previous WER version in the middle of our event, so if you notice this during an event then support can walk you through the process.

That might explain how my tiebreakers were so poor yesterday after WWDWWL over 6 rounds and ending up 4th in the Swiss. Cheers for the heads up - I'll pass it on!