Hmm... maybe similar.
New to drones & litchi, I set up a litchi mission, lots of close parallel lines, loaded it onto my Mavic Platinum Pro, so that as goinup says, I could release the controller and just watch it. The day was pretty windy, but nowhere near the drone's top airspeed. The drone went up, did a few of the parallel lines, seemed to get blown off course, took several minutes to resume course, got blown off again, never found the rest of the course. IIRC I pressed RTH.
I'd kinda thought it would follow a path, ie the lines, but on reflection, I'm guessing if it goes off course, it'll head straight to the next waypoint. But somehow it didn't. Since then, in low wind, I've had no problems. But why it behaved as it did, no idea.
BTW if you pressed RTH I guess you did have at least that much signal.
Also, your use of the word mission. If you'd loaded the litchi mission, then it lives in the drone itself, and loss of signal shouldn't have mattered. If you were just trying to control it in realtime like the DJI app, then signal loss is an issue.
Losing signal - IIRC there are options for different kinds of signal. Long time ago, I just chose the best one for distance, can't remember the options.