I just tried to duplicate this behavior using a clean instance of Hotcakes 3.0.1 and DNN 9.0.1 and was not able to.  I didn't do anything besides install both and run through the Hotcakes Commerce getting started wizard.  Then, I simply added the mini cart module to the page.  It works as expected. 
   https://www.screencast.com/t/cYUrxNnv1    It seems that your instance likely has modifications applied that are interfering with how Hotcakes Commerce works.
 
										Will Strohl, Upendo Ventures 
Hotcakes Cloud | 
Get Support | 
Code Support Official Cloud & Support provider for Hotcakes