I have also updated all the plugins and even reinstalled and still face the same issue. I will try to use the suggestion listed above but prefer not to have to alter any files. Please let me know if there is an additional update coming to fix this.

Update on the auction plugin. It does not allow users to select auction from the frontend, only admins from the backend.

When on front end your only selections for product type are simple or variable, where in back end, it includes the auction choice.

Im thinking that might need to be fixed from the Dokan end to work with the woocommerce simple auction plugin?

I bought woocommerce simple auctions and installed and it works wonderfully with Dokan, integrated seamlessly and LOVE it. Thanks for the recommendation!