Why can't a player see my hologram?

#Answer

Check, in this order:

• The hologram is enabled and its world is loaded.
• The player is within its View Distance.
• Who Can See It lets them: they have the View Permission, or were added with /pholo show for Manual.
• They were not hidden from it with /pholo hide, which lasts until /pholo show.
• The hologram follows them and Hide From Target is on.
• For a single line, its conditions pass for them.