There is a bug on the longer passages that just cuts it off and you have to reload the page to fix it and see the rest. It mostly happens when you spend too much time reading a passage.
Viewing post in Event Horizon - Legacy comments
I have no idea what's causing this and have been unable to replicate this bug in both itch.io and in the twine program itself. I recommend looking into your cookies and browser cache, or playing on desktop if you are not already.
Please note that this version of the game does not and will not receive updates.