I've found out that there is some weird interplay between bookmark navigators and slicers, resulting in selected navigator buttons while they are never actually selected.
Some information about when it happens: Create a powerBI file with 2 slicers, like category and subcategory.
Create 4 bookmarks, 2 for the first and 2 for the second slicer, one of which deselects all slicer choices, and another that selects one. Use "Data" only, and "selected visual" to select only the slicer you want to adjust. Duplicate the page, and sync the slicers,
Now make a selection, and swich back between page 1 and 2, In the beginning it will seem fine, but I THINK it goes wrong once you have selected a button pair that creates a combination of slicer selection resulting in no data. From that moment, all bets are off. Bookmark navigators will change their selected value, seemingly at random. The slicers will still be correct, but the bookmark navigators are wrong.
I made both a video and a sample file that shows the issue. In the sample file: Go to page 1, then page 2 and verify that both navigators and slicers are showing all categories and subcategories
Now on page 2, select both televisions only and handbags only, resulting in no data in the graph.
Now go back to page 1. I have no idea what you will see, but most likely, only 1 of your bookmark navigators will still be correct, the other, incorrect. You can then try some other combinations, and sometimes it will be right, sometimes wrong.
Seems like a REALLY nasty bug. When you are not showing the slicers, people will assume that what's on the buttons is correct, but it's actually wrong.PBIX example file