It's ve-ui-mwSaveDialog-editSummary-count in MWSaveDialog, but there are several issues with it:
- It should be stored in a variable, not searched for using jQuery .find() every time
- It should be modified with methods on OO.ui.LabelWidget, not jQuery .text()
- It should actually be visible
I don't know why it's being hidden, but display: none; is set on it, so maybe .hide() is called somewhere?