I have the same problem, and had a mobile service appointment scheduled for yesterday, which they canceled stating the part had not arrived.I guess they have an idea of what's causing the problem. Today they called me to reschedule the appointment for next Monday at their Sarasota Service Center. They said it needed a new harness, so it's cheaper for them to replace it at the shop rather than send a mobile technician. I asked if it was a bad sensor, and sight unseen they said it's the harness.
No loaner this time. They are now just giving Uber credits for same day service; very inconvenient for me, since I usually have a few errands to run every day. Anyway, I'm glad I haven't ordered the Tesla Offer power frunk. I'll wait for this problem to be resolved first.
I had this problem about 7 months ago too. Tesla Mobile Technician wound up replacing the entire frunk sensor and it's been fine ever since. I think it took him about 10 minutes in the parking lot at my company.