Maybe I'm nuts but I have a hard time believing that polishing the chamber fixed the issue. Wrong/bad buffer, bad headspace, bad gas problem (no pun intended), bad firing pin, break in, dry rifle or a trigger group problem sounds more likely to me. But what do I know? I'd be interested in knowing if it starts failing to cycle again.
Too bad about PSA customer service. I'm shocked by the state of QC and customer service in the gun industry. Regular/routine recalls. Poor or slow (no) response times. No returns, no refunds. I've owned dozens of "widgets" and never had as many problems as I have had since getting into guns. In military it was nice, I only had to deal with an armorer!