As of late I have been playing with ESP32’s, and ran into a problem of not being able to make a pin an output. It turns out that not all ESP32 pins can be true GPIO, but rather GPI (no O). Seems that all pins from 34 up can only be used as inputs, this also holds true when you try and remap a pin say to a SPI MOSI pin and you expect the pin to be a master out, this will not work, needs to be an input.
Then I found this image online and yes it now shows the 34-39 as GPI but also shows 32-33 as GPO!! ARGH! more questions, please discuss below if you have the answer!
I have since seen this video online of the issue being described in detail with a small demo too.