No Replies From Customer Support

Level 4
Having a problem with an item shipped. OU uses SurePost (a UPS-shipped item is shared/handed off to USPS). I shipped via a UPS label with tracking sent from OU, UPS sent it to USPS (which generates its own USPS tracking #), and now OU says I didn’t ship the item & will cancel the transaction in less than 2 days (because their original UPS tracking shows no activity).
I messaged Customer Support, also sent a message with screenshots through Facebook Messenger...still zero reply from them.
If they can’t resolve & cancel the transaction, I lose the sale, my merchandise, and look bad to my customer who bought the item.
SUPER FRUSTRATING that Customer Support does not respond to problems!!
Had an issue with repeat ID requests last September....messaged Customer Support so many times and never got a response, so just gave up.
Anyone know how to resolve this shipping problem, or have an actual way to speak to a person at Offer Up “customer support”?
Level 1
I’m having the EXACT SAME ISSUE. I shipped several days ago, and have PROOF that I dropped it off at post office, who accepted it! WTH are we supposed to do?? Offerup, GET AFTER IT!
Level 4
I even sent a private message to a Community Manager who was online at the reply from her either. There.Is.No.Seller.Support!