Hi @theo1979,
Are you trying to use PMPro and LifterLMS at the same time? Or are you trying switch from using PMPro to using LifterLMS?
If you are trying to use PMPro and LifterLMS at the same time, we’d like to know what features of PMPro you would like to continue using that is not already provided by LifterLMS. This will help us better understand your use case and make appropriate recommendations as needed. Note that since PMPro is also a third-party plugin, you will need to also consult with the support team of PMPro for the expertise on their software.
On the other hand, if you are switching from PMPro to LifterLMS, we do have our known issues listed in our GitHub page. Since LifterLMS is free, we recommend that you give it a try to see how well it works for you before you commit to using it on a live site.