we have tested it here with several USB-C Android phones and it should work. What phone do you have and are you sure it is USB OTG capable?
Also did you use the cable in the right direction? It will not work to use the USB-C to USB-A cable that have come with the phone together with the USB-OTG cable that comes the the Tentacle. You need to use a special USB-C OTG adapter cables and use this with the normal Tentacle Micro USB cable. I have attached you a photo to show what I mean.