CC2020 InDesign, multi document book, paragraph styles that force all text to the baseline grid, with space between paragraphs. Instead, occasionally and unpredictably, paragraphs will collapse so that all lines are laid on top of one another. Leading is not zero.

Solutions have been:
- Hard return, then delete the return
- add a single line after or before the paragraph to take the place of space-after
- move the text-wrapped image near the paragraph up or down.

None of these solutions work all the time, and sometimes none work.

WTF.