This applies to both my Apple TV and iPad.
Behaviour:
When using the search functionality, you type in the first letter and a bunch of results start to populate.
But as you finish the word or add new ones the results / thumbnails do not update. It seems that only results are shown on the screen from the first letter you typed. However if you do finish your search, even though what's displayed is incorrect - when you actually click the thumbnail, the updated result loads.
Tricky to explain, so I made a quick example video here for you which explains better:
I can replicate this behaviour on both devices, happens every time so is consistent for me.
Let me know if you need any more info.
Thanks