I found a little thing today that flummoxed me for a few hours.
I was republishing a pbix file where I had chnaged the date slicer to be a relative date slicer. No matter how many times I republished the report online would not update the date slicer which was still showing as a 'between' rather than 'relative'.
Publishing to a test workspace worked fine no problem but the existing report would not update. Then I noticed that the 'reset to default' button was highlighted. I reset to defaut and it re-assigned the date slicer from between to relative.
I just thought I would post in case anyone else flails around for an hour wondering why the heck the format doesn't update!