I experienced the same problem with one of my datasets online. Initially, when I publish the Field Parameter-driven slicer, clicking on slicer selections has no affect on the visuals using the parameter value. However, I entered "Edit" mode online, click a few slicer buttons - which still didn't change the visuals - clicked back to "Reading" mode SAVING my changes, and it then started working again. I can confirm this with two separate browsers - Edge Beta (v102 base) and Chrome (also v102), with a video of me showing it not working in Chrome, editing the report, saving back to reading mode, and it then functioning as expected. Others in my organization were able to have it working for them without editing the report. Hope this helps others figure out what's going on. Love the feature. Can't use it as is if fails like this for everyone.