CrownCollective
That's certainly an option! Separation to two tracks (multiplayer/singleplayer) with equal awards would be a possible fix. If the awards were different, we're probably back to the main point OP was making: that they won't get the multiplayer awards.
My concern with equal awards is if the multiplayer ones take longer due to the time it takes to party up and complete things together. There isn't a reason for multiplayer at all. I too keep the multiplayer ones for last typically, and it certainly is more of a hurdle like you said!
Quite the puzzle indeed. Maybe a solution for everyone would be if the singleplayer track were scaled in difficulty to have more challenges which take longer?
If the estimated time to completion were more similar, that could be a possible answer. Meaning, if you want to do multiplayer, it's fewer challenges, but the extra time it takes to complete things with 2-4 players equates to the estimated completion time of the single-player track with more challenges.
Thank you EA_cuervo for passing it along; it's certainly interesting!