I'm having the same issue right now. I have approx 14 tabs/reports in my model and all but 2 have the DrillThrough in the filter panel, which I'm using between 2 of the reports, but on 2 of my reports, the DrillThrough is not there but it shows ToolTip there. Those other reports hwoing the DrillThrough do not show the ToolTip.
I'm using the latest November release right now as well. These are examples of 2 reports in the same PBIX