My package hasn't moved in 10 days. What's going on?

AQ343506971CN
In Transit
China
China Post
United States
2022-02-16 23:00Shanghai, leaving [Shanghai International Processing Center] has been exported to Shanghai

Destination
Origin - Sync Time: 2022-02-25 00:30:17 (GMT-05:00)
2022-02-16 23:00
Shanghai, leaving [Shanghai International Processing Center] has been exported to Shanghai
2022-02-15 15:43
Shanghai, arrive at Shanghai International Processing Center Shanghai
2022-02-12 17:21
Shanghai Municipality, [International Express Logistics Business Department] has been received and sent, the contractor: He Xiukang, Tel: 18917040271

My package LZ786015936CN has been stuck as “ Shanghai, Arrival at Shanghai International Mail Exchange (via)” since April 13 after being bounced between several regional sorting centres back to back. It was supposed to be here by the 27th at the latest but instead it’s been back and forth around China since the 8th and now is stuck in Shanghai. I contacted the seller and they said they can’t do anything. Is it lost? What do I do? It’s a $70 package.

Hi
My parcel, LZ410973801CN, appears to be stuck in Shanghai. Latest tracking information is:
Shanghai, to shanghai exchange station (transit).
What does that mean? Where is my parcel now?
Thanks