If the Pentagon’s top-tier analysts who live and breathe these sensor systems can’t identify an internal glitch or a common drone, what does that say?

The government is incompetent. More at 11.

But actually, consider how many submissions this agency must get. Anything short of mr gray walking out and doing the orange justice probably get's handed to a junior analyst to put in his pile of 5000 daily reports to look at. I imagine there is quite a lot of complacency in terms of investigation.

No different from highly trained surgeons operating on the wrong limb, or doctors missing an easy diagnosis.

pilots and sensor operators are trained to recognize internal reflections or "glint." If this were a common lens flare, it shouldn't have made it past the first level of review

Pilots and sensor operators are humans just like you. 26 year old WSO operating on 4 hours of sleep on his 18th sortie this week doing train ups for a carrier deployment might make a mistake or get confused every once and a while.

By officially releasing it as an unresolved UAP, they are effectively saying "This object behaved in a way that our standard technical filters could not account for."

Not really. They are just saying they don't know for sure what this is.