I was able to add comments in one of my excel files, by right clicking the target cell and then selecting add comment. However suddenly add comment option disappeared from the right click menu and also from the riboon's Review tab. So created a new blank excel file and tried the same. But as you can see in below screenshot, anything related to comments was simply disappeared from excel (Microsoft Office Professional Plus 2016):
Compare this with the excel from other laptop (Microsoft Office 365 ProPlus):
Why this is so?
Best Answer
Got this issue too, tried to solve it, but instead found an alternative way to insert a comment:
It worked fine for me.