I just finished the cleaning/inspecting of my Shield, I did not see anything that looked out of the ordinary to me.

I reassembled the pistol BONE dry, then hand cycled the slide.
Twice it locked open out of maybe 50 cycles, when this happens the barrel is tight. I can NOT wiggle the barrel with the slide stuck open & I can't tell where it's bound up, smack the back of the slide with the palm of my hand and it goes forward.

I took it apart again, this time I reassembled DRIPPING WET with oil. Then hand cycled the slide 100 times without it locking back.
This maybe from not being able to slam the slide open with my aging hands.
I will hand cycle it a few times in the next week, and follow up with a trip to the range next weekend then report back with my results.