I have made modpack that works fine in my custom profile.
I have exported it, uploaded it, has been approved. Yet once you install that modpack it will crash on startup.
I have deleted every single mod by mod in that downloaded modpack profile to find any issue related to a mod. None!
Once the folder was empty the game works fine. So my guess was that twitch/curse isn't installing the profile correctly.
So i tried the following:
I have also ftb beyond installed, i opened that folder and deleted everything inside and then copy pasted everything what's inside the my modpack that was downloaded from twitch/curse app. Guess what it works properly now.
So now i'm 100% sure something goes wrong when twitch/curse is installing the modpack or setting up the profile.