Test document (Cannot upload an .xlsx file here, so posting a demo viewer link)
There are two issues. One is with horizontal scrolling. Try scrolling 1 column to the right in the doc above. (May need to reduce browser window width) You’ll see that the text in row 1 has disappeared. (Screenshots below) It seems that cell overflow content is only displayed if the cell itself is visible.
The other issue is with overflow content in the cell P9 on the right. It’s also discarded, this time because it wasn’t accounted for when the .NET conversion code was calculating spreadsheet width.
Both Excel and LibreOffice display such documents, so we’re hoping to be able to handle them as well. In practice, surprising number of people create spreadsheets like that, without using text wrapping.