The extractor is losing its grip on the case, and without a live round rising in the mag to assist ejection, the spent case is left in the port.
Yup. No doubt about it.
In my opinion, the tipping and rolling test is a good field expedient method but I want a test that is more definitive.
There is a simple extractor diagnostic test I learned while taking a class with Hilton Yam. I call it the Hilton Yam Ultimate Extractor Test although he doesn't have such a grandiose name for it and he's not the original inventor of it.
Step 1 - fill a magazine with cartridges
Step 2 - insert the magazine into the pistol
Step 3 - load a round into the chamber
Step 4 - remove the magazine from the pistol
Step 5 - fire the loaded round while observing the case as it ejects
Repeat Steps 1 through 5 until all the cartridges in the magazine are expended making sure to remove the magazine each time before firing the round.
If any of the ejected cases drop through the magazine well, this is proof that the extractor needs serious attention. If any of the ejected cases fly off in different directions, the extractor needs less serious attention. Either way the extractor needs attention.
What this test does is eliminate the magazine as a factor influencing ejection. Often times a less than optimally fit extractor will lose control of a fired case and it's the sudden upward movement of the magazine follower lifting the next round into position that pushes the fired case out of the ejection port instead of the ejector.