This has happened before and I don't know what triggers it (other than the expected bulk metadata changes)
I renamed (consolidated) a couple of series. (using the Manage Series PI)
Changed 1 to a hierarchical name (made it a child of another series) (used Rename in the Tag Browser)
Added a couple of formats to books (my normal way, DnD)
I DID NOT:
rename/delete any tags.
run Modify EPUB or Quality Check on a block of files
count pages on a block of files
The Authors are varied
The
series seem to be involved, I see multiple books belonging to
a whole series. Some hierarchical (but not all), some only 1 out of many.
{ID} is all over the board
No obvious pattern
