Wheel Chock sliding

[Skelee]

I bought a front wheel chock at princess auto. It worked great last year. This year it is sliding and the front feet fell off.

https://www.princessauto.com/en/detail/motorcycle-wheel-chock/A-p8674285e

I used gorilla glue for the rubber feet. I checked tire pressures etc.
I use it at end of driveway, free standing.
I don't have a wall to put up against.

any ideas to stop it moving?

Thanks