Best I can tell, it started around 3/16. I haven't gone back through all of my Paypal payments to see if I missed any overpayments.
I realized what was happening on the 19th.
I'm having to refund overpayments if customers check out before I can send a corrected invoice.
I believe it's a problem on this end because 1) the post on this board that someone else wrote about My eBay Pref. not being applied. And 2) no one has posted anything similar to our problem anywhere on eBay. If it was an eBay issue, it would be a lot more prevalent.