Your problem probbaly lays in the plug itself, take a look at your cabels, i guess that the plug on the OTG cabel (the metal that plugs into the tablet)is shorter than on you charging cabel, its a known problem
Cut a little of the plastic on the OTG so it gets as long as the other cabel, and it vill probbaly work
Yes, the original charging cable has a slightly longer connector, but my Aukey usb-c cable doesn’t and it works well. When I boot up the tablet the OTG adaptor briefly provides 5V power, then shuts off.