Anki Mobile - iPad: ability to edit pen-drawn images seems intermittent

First draft of this post:
Using a two-finger touch to open a drawing (i.e., image created with an Apple pencil) field for editing while browsing a note seems to work only on the first of such fields within a note. Is this a known limitation, or is there something I need to know to edit subsequent image fields within a note?

“You can later edit a drawn image by holding two fingers on it.” – from the discussion of Adding::Pen at Adding & Editing - AnkiMobile Manual

Subsequent edit of post:
I retract “seems to work only on the first of such fields.” Further experiment leaves me baffled as to why the two-finger press works sometimes and not others, regardless of which image field or whether there are multiple such fields in the note.

In one note, the first image field was drawn with the Apple pencil. The other two were pasted after cutting them from the first field. Only the first can be opened for editing with a two-finger press. OK, so maybe pasted images can’t be thus edited. But in another note containing five pencil-drawn fields, whether they open for editing seems random: any given field sometimes opens, sometimes not.

Third edit:
Hypothesis (1): pasted fields may not be edited, even if they were cut from another pencil-drawn field.
Hypothesis (2): the software is sensitive to where in the field (as displayed during browse) the two fingers are placed. If they are placed in white space “too far” from drawn pixels, the field won’t open for editing.

I can confirm that copying&pasting drawn images will break the link to the original drawing data. I’ve made a note to look into whether it’s possible to preserve the link when pasting.

I believe I’ve found a workaround that suits my needs.

If, instead of pasting into a card field, I open the field as a (new) drawing, and then paste into the drawing, the drawing – including its pasted content – may be edited.