Undefined error after “start now” button

Hello,

I have a problem with “start now” button. I searched the forum and tried to implement all your advice but it still doesn’t work. When I press the “start now” button, I get an error 404 page and the link of my page is transferred to: https://mydomain.com/courses/name-of-course/undefined

I set up the permalinks in my settings as you stated (https://prnt.sc/2mYIhr1n_ye5) and updates several times.

I also leave you screenshots of my leanpress -> settings -> general (https://prnt.sc/_4v1YofWxyXv)

and screenshot of my learnpress -> settings -> permalinks (https://prnt.sc/ot1Pzfv32RYb)

Thanks in advance!