I was given an Excel spreadsheet which I opened with Excel 2016. It seems to have some rows which are hard to access: in the screenshot below, you can see the row numbers jump from 2 to 338 and from 343 to 375. There is data in these rows that I want to access. The document properties (second screenshot) says that there are hidden rows. I tried selecting the entire spreadsheet and choosing Unhide, or selecting the entire spreadsheet and setting all row heights to 20 pixels, but these rows won't appear.
What is going on, and how can I get all rows to appear?