After converting a Lead, then going to the Account page, the previous notes do not show. This is expected. Clicking the "Show All Notes" checkbox should display all notes made on all Contacts for the Account. But, clicking this checkbox seems to do nothing.

Everyone in our office is using Google Chrome.

I have not had any issues with this specifically, but my colleagues have. 

I have had a quick glance through the difference in the settings and can't tell anything major.

Is there a plugin or something I am missing to make this functional again?