Sounds like it's short stroking or a mag problem.
Check ejector and extractor
Is it is happening with multiple magazines?
May just need a deep cleaning and a lube
To date, I changed recoil spring and put fresh springs into 2 mags that were experiencing these issues. No effect. Next, I thoroughly cleaned everything including the chamber. I normally clean after every session but don't ever use a wire brush for the bore, but I did use one now. Seems to have changed things a bit, but was still having issues. Last thing I did was get a new mag and here is what I started seeing after a thorough clean.
This happens much more frequently with the old mags but also happened a few times with the new mag. My next step was to detail strip everything and clean inside and out. Ran into a bit of a snag. Can't seem to remove the slide pin holding the block in place. It looks like a simple procedure, but mine just wont come out and I won't force it... anymore.