Did you install all drivers ok?
I have used a couple of USB OTG adaptors with memory stick and even micro sd with usb adaptor and all worked fine.
Even installed Windows upgrade with it as not enough space on Tablet to upgrade directly.
Later I did a full wipe and reinstall of both systems but OTG stll works, can’t remember where but I found a driver pack that installed everything.
Try a search for X98 driver pack.
