Certain behaviours of my 2016 MacBook Pro baffle me. Earlier today this happened:
The left side Thunderbolt ports stopped accepting power, then my USB mouse stopped working, a few seconds later the HDMI signal cut out. The right side worked and a reboot fixed everything. 🤔 😕

@mangochutney I have that model. Twice now my computer has shut off unexpectedly with 0 battery even though plugged in. I too usually plug in power on the left. I now have the battery level in the Menu Bar to keep an eye on it. I'd blamed the socket rather than the machine, so your experience is interesting.