I encountered the same issue and my guess is that the UiPath only can read data which is loaded on the screen. For example, some websites load all the query results on a screen at once (but not shows it on the page and some will be shown on different pages). The others only load data which can be shown on a page and then they send query when “next page” is clicked on. At least in my case, the next page selector worked for the former case and not for the latter.
(Again, it’s just my guess. I might need to set up differently for the latter case)
I gave up to use next page selector and used “find element” to find “next page”, then I used “click” if there’s the element and again use data scraping.
Note that datatable doesn’t clear automatically, so the data on the next page will be simply added to the datatable which has the data on the first page.
Hope there’s an actual solution…