If it is happening only after you fire the reloaded round it may be the cut in your chamber. Can you measure one of the stuck fired cases necks for the diameter and see if it grows. It may be a optical illusion but the photo you shared looks like a bell on the end where the chamfer is.
Thought is that you chamfered them deep and with the brass getting harder from not annealing it is expanding to a slight groove in the chamber where the reamer stopped.
On soft brass you probably don’t notice it, ejecting it puts it back to spec. With the harder brass it becomes way more noticeable then sticking occurs.
You said the brass had 5 firings on it. But you didn’t have issues on the first 4 firings which would basically rule out the seating die.