I'm close to beating the Ender Dragon and I waited for three days but no phantoms have spawned, I would've died to see if it's a bug or a glitch but I'm on Hardcore Mode so dying isn't an option.
Note: I haven't seen anyone report this and I'm not entirely sure if it's a bug or a glitch
Did you check the game rule
doInsomnia? What does "Time Since Last Rest" say in statistics? Can you attach your world to this report?