World file that you can reproduce 
Step to reproduce:
1.  open world file

2. put left shulker into that chest, any amount you want then array will start

3. watch hopper at x  -12, y 41, z 139. its never powered, and its facing powered rail.

4. it would get item and chest minecarts goes through its front side soon but it won't push items into chest minecart

expected : it should push items into chest minecart like other / nearby hoppers as it should do, and chest minecart is not too fast its always slower than 20blocks per second.

5. if chest minecarts with less item amount / empty comes later then it pushes item into that.

Its able to reproduce automatically at world file. there could be more 'dead' hoppers if you change its accerlation by replacing rails or powered rails.