As Toyah Wilcox would sing.....'It's a Mystery'

The problem you are describing conforms to none of the usual issues reported.

Having checked your ejector, extractor and hammer and trigger pins and firing pin for breakages, I can't think of anything else other than bent guide rods on the bolt or something stuck in the trigger recess??? These are just shots in the dark though...why some ammo would cycle negates both these theories though. Let us know what the issue is when you find it. FYI mine loves CCI sv. Unless your rifle is now allergic to CCI?