I too have a tablet not made by Wacom. For some reason, Illustrator only opens the tablet-sensitive definitions for Wacom. The solution I found: Go to the Wacom site, install the latest intuos driver. You won't be using it, but it will trick Illustrator into thinking there's a Wacom installed, the definitions will be active for your pen. Mine seems to work fine now.
Wacom.com has free driver updates. Click on support, then on drivers. It will have a list of all their product driver updates available. Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/jennifer_2cda060d2c48cd81