Subtitle placement, video zoom or the screen’s picture-size setting may be pushing the text outside the visible area.
Why this happens
A subtitle can be present and correctly timed while still being difficult to read because it sits too low on the screen. This is a placement problem, not necessarily a missing track. Enlarging or cropping the picture can hide text near the edge, and some subtitle formats have their own positioning instructions. Compare the subtitle with other edge details, such as a channel logo, to see whether the whole image is being enlarged or only the text is misplaced.
Return any recent zoom or crop change to its normal value before moving the subtitle. Where the installed player offers a documented position or vertical-margin setting, use a small adjustment and compare a two-line caption. Kodi documents separate subtitle-position and margin behavior, including differences between temporary and saved positions. Other applications may not offer the same controls. Keep the effect of the change visible on both short and long captions, and avoid making a global adjustment based on one unusually styled scene. A different track can be a useful comparison when only one format is affected.
A useful way to work through it
Undo recent picture zoom/crop changes and compare other edge graphics.
Move subtitles only with a supported position or margin control.
Test a two-line caption and keep the original placement value.