I think we're going to need some screen shots, and they should show the layers panel expaned for the page where the text is disappearing, but you should also check the story editor to see if the text has gone into overset, and at what point. That will also help pin down the problem.
Oh, I should clarify, the two text frames representing two pages are on one elongated page (artboard). So not really two separate pages as such.
No <p> symbols after the page break so no reason why it should be jumping into invisibility like that (by the way).
A page break is a page break, meaning you told ID to move the text to the next physical page (we don't use the term "artboard" in ID the way you would in Illustrator). If you have one large page (look in the Pages panel to see waht ID considers a page in your document) set up with multiple columns representing 2 "page" panels, you need to use the frame break or column break, not a page break, but you'd really be better off setting up as facing pages spreads, where each page is the correct size.