Confirm the current item actually ended
Note whether the playhead reached the current file’s end and whether the image remains on its last frame. Compare this with a pause in the middle of a programme. An end-of-item hold is a different state from waiting for more media before the end.
Inspect the playlist and confirm a next entry is present. The stable manual distinguishes the normal exit/progression behaviour, a keep-open choice for the last entry and an always choice applying before later entries too. The value matters more than the general statement that keep-open is enabled.
Read the exact preference value
According to mpv, keep-open=yes keeps the final playlist entry open, while keep-open=always also holds earlier entries and prevents automatic advancement. If the intended task is sequential viewing, compare the value with that goal rather than repeatedly adding the same next file.
Keep the related pause preference separate: keep-open-pause changes whether the end state pauses or stops in its documented manner. Neither choice establishes that a later URL can play. These are player lifecycle controls, while a file-open or network error belongs to a later attempt to load the next item.
Test progression and access separately
After preserving the prior setting, make a deliberate comparison on two permitted files using the desired progression behaviour. Confirm whether the second item is selected automatically. Then record whether that second item actually opens and plays; selection and successful playback are different results.
For help, provide mpv version, playlist order, keep-open value, end position and any error produced when the next item is attempted. Do not treat the option as a promise that the player can never exit, because the manual documents exceptional conditions. This evidence distinguishes an intentional hold at file end from an absent playlist entry or a genuinely failing next source.