Roku says "control by mobile apps" is disabled — how do I fix it?

Your Roku is refusing app control by policy, not by malfunction. Rokus have a setting that governs whether devices on your network may control them, and on some devices (or after certain resets) it's set to Disabled. The fix is one menu path, on the Roku itself:

Settings → System → Advanced system settings → Control by mobile apps → Network access → Default

• Default — devices on your home network can control the Roku. This is the right setting for phone remotes.
• Permissive — also allows control across subnets (some mesh/router setups need this if Default still fails).
• Disabled — blocks every remote app, official Roku app included.

The chicken-and-egg problem: changing the setting requires navigating the Roku, which is hard if the remote is lost. Your options: a Roku TV's physical buttons (panel edge or back), an HDMI-CEC remote from any plugged-in device, or finding the old remote one last time. Full rescue playbook: lost Roku remote.

Remote Pro detects this exact refusal (the Roku answers, but rejects commands) and shows you the setting path in-app instead of failing silently. Once set to Default, control is instant — Roku needs no pairing at all. If the Roku isn't showing up in the scan at all, that's a different problem: the empty-scan checklist.