It seems there is a large variety of bugs affecting different people, some people have dev mods working fine but the user mods not, and some have said it's the other way around.
I've done so tests based on my system which can be seen here: https://youtu.be/0v-bo14QHWU
Maybe this discussion can be a collection of issues people are facing along with their system details. Hopefully the modders themselves will also look at what issues some are facing,as the most common is bad unit spacing. The only one (other than dev mods) that my system hasn't had ANY issues with has been those from CJH.