Apple TV 4K volume not working with Hisense

Next, check that your TV has an IR receptor to receive remote signals, and verify that this IR receptor has an unobstructed line-of-sight from the remote. [Some people have been known to put small items on the same shelf as the TV, that could potentially block the receptor.]

TVs that work with a bundled bluetooth remote, may not have an IR receptor, perhaps.

Next, check the setting for the remote on Apple TV in Settings﹥Remotes and Devices﹥Volume Control﹥.

If it is set to Auto (when that doesn’t work), the try TV via IR option.

The Learn New Device option is only for TVs (or audio systems) that use non-standard IR signals for volume control. The standard IR signals for volume control should work for most TVs (or audio systems).

The volume worked in the past.

Please do this procedure, if it worked before with the same setup.

If the volume buttons on your Apple TV remote stop working - Apple Support