Thanks @alextil
I'm glad I haven't (completely) lost my mind.
I haven't had any progress with this issue besides creating a workaround with a Proto and some Grove ports- assembling a sort of..."Port Board." It certainly isn't pretty, but here's a pic for fun:
0_1575484624725_PortBoard-cc.jpg
It's 2 "Port B"s - to accommodate devices that want GP26, GP36, or BOTH. And a simple male header to Serial2. (16/17)
I've had some thoughts on other things to try (mostly in configuration or digging deeper into M5 and ESP32 libraries), but have been busy with another project that requires much smaller hardware. If you (or anyone) find something that in any way changes this functionality, please post.
All info helps.
-Atlas