Help tracking WM_APP + 12316 message flood



I have a c11 app that freezes for several seconds. During this “freeze” there is a flood of WM_APP + 12316 messages.

Not sure if my code is the source of these messages or not. I’ve searched for 12316, B01c, 301c, 45084 w/o any luck.

Anyone have a suggestion on how to narrow down the source of the messages?