Deafening....
edited to add:
In an email from ESRI tech-support I'm told:
Thanks for reaching out. Development recently commented that BUG-000112192 is fixed in the current Beta ArcGIS Pro version. So, it looks like a fix will be pushed out in the next publicly available patch. I hope that we see this soon, but I unfortunately don't have a definitive time frame.
That should just about do it....