Ahh, I understand what you mean! The size I was using was 32, and the height was 150. 32 x 5 = 160, which was the height that I coincidentally changed it to, which fixed things. I'll be running some tests with the attached dialog sample script with a size of 2, the first index being a long string that the text box can't cover fully, and the second index being a short string that the text can more than cover fully: Setting the height to 150 and the size to 30 also fixed things. And as you said, I tried testing incompatible multiples of 150 between all vertical limit modes just to be safe. (along with a read delay of 0.1) It only affects the auto pause full effect.
When changing the read delay to 0, things seem a bit weird. With auto-pause, it seemed show just the last four lines of text (of the longer string), with auto pause full only showing the last two lines of text. (the short-string index was also missing for some reason) Setting the size to 30 to be compatible with the 150 (with auto pause full) just shows the last line, while with auto pause showing only two of the last lines, yet the string on the short-stringed index was missing entirely, despite it appearing on the inspector text.
I don't think anything in my current project should be adversely affecting this, but I may as well isolate the testing into a new unity project.
However, the effects still appear the same. As long as there is some read delay, (and keeping size a multiple of height in regards to auto pause full), everything is all there, no disappearances of text. While I don't plan on leaving the delay to 0, I do find this to be strange behavior, or maybe what I'm experiencing is due to me not activating a certain other setting in the component?