Sent one of my top guys out last night. Tried to recall him today from the wasteland to see he has been out exploring for 2000+ days and a return time of 1000+ days. Had this happen before with my food, water and power when I started the game offline. The resource times were fixed once I connected to WiFi. Tried doing that for my dweller but his recall time won't change and I don't feel like waiting over 3 years for him lol. If nobody has a fix or it isn't a planned fix for a future update. I'll try what I can to fix it myself. Try to kill him and see if it fixes him or something.