I need help for a very similar problem:

NO merged cells
NO specialized formatting, and format is consistent across spreadsheet
cells are set to "wrap text"

When I click on "autofit row height", 90% of the rows become the correct
height, while 10% do not. I have a few thousand rows of data, and 26 columns
with varying amounts of text in them. Sometimes the row becomes too short,
sometimes too tall, and it can happen no matter how much or how little text
is in it.

Can I repeat that I DO NOT have any merged cells? I have searched online
for hours and no one seems to have an explanation or a solution.