Copy the contents of the spreadsheet to a new one, and deleted the old one (it wasn't a particularly important spreadsheet, thankfully), and everything was fine.
I can only assume that somehow the file had become corrupted.
However, for some reason, the value calculated by the formula does not update automatically. We already had the calculation options set to automatic and didn't know why values weren't updating.
I am having to click on the formula bar, then I have to click enter for the formula cell to do its thing. F9 and Shift F9 didn't help and left the values the same.
Zero knowledge of Markdown is required in order to write well-structured documents with Writage.
This article shows you how to add, update, or remove an application in Azure AD.