After testing this some more, it appears you are correct, Warmane. Even without the imp, party members will still be hostile if you return to camp using the waypoint during the day. Without the imp, they will not be hostile if using the "End the day" button. However, if you DO have an imp and use the "End the day" button, they will still be hostile. So there's some sort of issue both with having an imp, and with returning during the day (as two separate issues).
Last edited by Marktheshark; 09/10/20 12:08 AM.