Retool has rolled out unique identifiers (UUID) for app pages. If you use Source Control, Retool recommends that you create a new branch with no changes and push it to Source Control. If you use Retool Cloud or self-hosted Retool 3.191-edge or later, Retool automatically creates a migration commit to add UUIDs to each page. Once you merge this commit, you can successfully configure per-page permissions on your protected app.
Note: If you are working on more than one branch before the UUID addition in version 3.191-edge, Retool runs the migration on each of those branches, and the branches will end up with different UUIDs. Make sure add UUIDs only once, do not override the UUIDs on the main branch after adding them. Doing so results in the inability to set per-page permissions, because the IDs initially set on main are the ones that Retool will use.