When reports with "Reveal my email address" ticked are sent, the editor’s e-mail address is not actually included in the e-mail headers so they can be replied to.

The last working report that I can readily find is from December 6th and the first readily found report with this broken is from December 10th, so I reckon this broke with the 2019-12-09 update.

Looking over the changelog doesn’t really reveal an obvious culprit though.