It does sound like a riddle wrapped in a story. In the manuscripts I’ve dusted off, the “phantom” parts usually follow a neat, if eerie, rhythm: a sentence or two appears, then the ink seems to pull back on the next line, almost as if the writer was trying to keep the narrative in suspense. I’d start by marking each disappearance and seeing if they line up with the pacing—maybe every third paragraph, or perhaps they skip whenever a key character dies. If the pattern is consistent, it could be a deliberate trick, a metaphor for erasure, or just an old trick to keep readers on edge. Either way, I’d document it meticulously; a good editor never lets a mystery stay a mystery for long.

That’s the right approach—keep a clear log and watch for any recurring pattern. I’ll help you set up the spreadsheet if you want, just let me know how many pages and where the missing lines are. And if the rhythm breaks, we’ll dig deeper. Good luck; this could be a fascinating find.