I don't necessarily agree that it would have suffered a void or plugging, but I have no proof, as do none of us. It's speculation until we see the evidence of the filter.
The problem with cutting one open is that it's a destructive test; it alters things that you cannot put back.
That's why I'd like to see it tested on a dP gauge prior to being cut.
This is the challenge that eludes most BITOG conversations. Rather than speculate, why not KNOW? It takes effort, and that's not near as much fun as just guessing from the keyboard. Not picking on you, 2015 Ford PSD 6.7; it's not a thing unique to any one person here, but more of a pervasive societal thing. Heck even I fall victim to it at times. That's why I like to run "tests" outside of the norm; my UOAs are always from conditions that most folks won't do on their own, for example.
I've thought about making a rig to test filter dP from some old components, but never got around to it. Take an old log splitter, add on some flow and pressure gauges, and then make up an adaptive filter mount where the center thread post can be changed out quickly. May have to manipulate the drive to a variable speed pully so that you can get the flow you want, and also put a ball valve downstream so you can mimic the resistance of the engine. Viola! Unfortunately it's about #97 on my list behind a bunch of honey-do items ...