Catching this before bed again, it could just be that when the read delay is 0, it's skipping to the end of the text and otherwise behaving fine? If you can send me a sample scene to my email posted on my website, I can check for sure!
Good afternoon! Sorry for the super late reply, but I will be emailing you later today! Attached in the email are all the files I've created for a default scene, along with three game objects under a canvas: One where the text is a multiple of height, one where the text is not a multiple height where each have tests for auto pause without delay, auto pause with delay, auto pause full without delay, and auto pause full with delay (interestingly, with auto pause full and a delay of 0.1 it seems to cut text), and my own example that I've been working on (one with a multiple height, and one without. The already active object of multiple of height that highlights the problem). I hope we can gain a better understanding of this. :)