confused how ripscore works

I'm not sure of all the ways to get rip score but I know you for sure get some each time you open a loot box, and probably for completing the missions/quests. Completing challenge goals gives you the rip coins to open the boxes.

I have opened 12 boxes today after doing all challenges and I got a total of 60 rip score! More than half the boxes didn't reward me any RIP score at all! I'm starting to really resent this game because doing every challenge in co op and earning cash to buy boxes to get rip score for each box only to not get anything except town rep and a random title is absolutely insulting and downright frustrating!!!