Keep the series label and episode separate
Atresplayer explains that its series-level HD indication can reflect only some of that programme’s videos. An earlier episode without the expected quality can therefore be different from a new episode that supplied the label. Keep the season and episode number when investigating; a screenshot of the series heading alone does not identify the video actually being played.
Inspect the quality choices offered for that video
The FAQ describes selecting from the qualities available for the content. AUTO is the default and chooses according to the available connection. Distinguish an absent high-quality choice from an offered choice that is not currently being delivered smoothly. The first observation concerns the options for that item; the second also requires looking at the playback conditions.
Compare a matched episode rather than a different programme
For example, a television and a tablet can appear to disagree when one is on the series landing page and the other is playing an older episode. Open the same episode on both before comparing. Preserve the exact item and chosen quality so a later test does not silently replace the video with another instalment that has different options.
Do not use the highest setting as a universal repair
Atresplayer warns that choosing maximum quality without enough bandwidth can produce interruptions, and describes automatic adaptation on iPhone and iPad. When the desired option is present, compare AUTO with the intended setting using that same passage. When it is absent, report the episode and visible choices rather than assuming a faster connection will add a version the player is not offering.
Questions, answered
Can one HD episode cause the series to carry an HD indication?
Yes. That is the explanation in Atresplayer’s feature FAQ.
Should I force maximum quality whenever the picture is disappointing?
The publisher warns that insufficient bandwidth at maximum quality can cause interruptions.