The released versions of Couchbase are not able to efficiently page through the documents, thus the farther down the list you go, the heavier the load on the server to get the next page (and the longer it will take). As a result, the UI attempts to prevent you from going past document #1000, though you’ve discovered a bug that lets you get around that. If you’re willing to risk the extra load on the server, you can keep going. (Another way around is to edit the URL manually to specify a page past 10.)
We are working on the ability to efficiently page through all the documents for a future release, which would avoid this problem/limitation.