Why does enabling pre-release updates not offer the build I expect?

Ordinary pre-releases and internal pre-releases are separate update channels. Open Settings > Application > Updates, enable Receive pre-release updates, then enable Receive internal pre-release updates if you specifically want internal builds. Run Check for Updates and read the result in About.

A channel preference makes matching releases eligible. The update feed still determines which builds are offered. Not every internal release is distributed through automatic updates, and eligibility also depends on processor architecture and the releases supplied by the update feed. A failed check is different from a successful check that finds no update.

Internal builds can contain unfinished or experimental changes. If a requested build is not offered, check the official BetterDisplay download information for its availability instead of assuming that repeating the check will expose it.

Turning a test-channel preference off does not immediately replace an installed test build with a stable build. An installed pre-release retains pre-release eligibility until a stable release replaces it. An internal build similarly retains internal-channel eligibility.

Do not identify the update channel solely from a version number or download filename. A release candidate can use the same app version string as a stable release. BetterDisplay’s built-in updater uses the update feed’s channel information together with its eligibility settings. A third-party updater that uses only the bundle version can classify the same release differently.

See Updates for channel behavior and installation choices.