Have received two offers from nomads to join me, even though the 'Accept' button is greyed out. This may have occurred due to the fact that the quest is still active as one nomad is still in hospital and can't leave, even though all other nomads have left. Images attached, save file not attached as too large. Suggestion would be that any nomads that have left aren't able to spawn the join offer, though not a huge issue as you can just reject all offers.
Save file is here: https://wetransfer.com/downloads/aba962209847c061f51d687e04fd81a020200816165538/49f2f36b0246a39e6e685f95a2dbf18c20200816165556/d2cb05
Thanks for the report! The attached save file was very useful. This has been logged as a bug.