Quick and dirty PDF annotation works on Mac, not iOS. Why?

Scrivener Scrivener for iOS
1

More thorough annotation of PDF:s I make with PDF Expert on my iPad Pro. If I send a (flattened) copy from PDF Expert to Scrivener, I can read any notes I’ve made with Apple Pencil in Scrivener iOS and (after syncing) also on my Mac.

If I open a PDF in the Files App and make some notes on it with the Pencil and then copy the document to Scrivener, the scribbled notes do not turn up in Scrivener iOS, but they are there when i open the same PDF (after having synced with DB) on my Mac. Seems a bit weird to me.

Also, if I open my annotated File PDF in PDF Expert on my iPad, the scribbled notes are there. If I send this copy to Scrivener iOS, it shows up annotated in Scrivener, both on iOS and Mac.

Definitely not a deal-breaker, but somewhat of an annoyance. And Weird … Especially the fact that the same PDF, once in Scrivener and synced, looks different on the Mac from what it looks at the iPad.

2

Sorry to bump my own query. But, as it’s soon been posted for a month, without any reaction, and the problem persists, I’m curious as to what causes it.

As I said:

To summarise:

  1. I open a PDF in the Files app.
  2. I make some note on it with my finger (on the phone) or Pencil (on iPad Pro)
  3. I open it in Scrivener iOS. The note I’ve made is not there.
  4. I sync Scrivener and open the project on my Mac. The note is visible on the Mac.
  5. I sync the project back to iOS. Still no note visible.

i.e. the PDF, synced back and forth between iOS and mac looks different depending on if I’m working on my iPad or on my Mac.

Weird, isn’t it?