AI hallucinating when uploading big PDF's

So i uploaded a PDF with around 300 pages. Everything works fine until you ask something about page 200 and above. The AI confidently tells me that there is stuff about some plane crashes and how to use markdown. This is nowhere in my PDF and the AI can’t find the topics that are actually on these pages. I can’t even explain how that works and the AI really thinks that the stuff is in there, even tho i study Cybersecurity. Please tell me a workaround until you got the issue fixed. I need to study for my exams. Should i divide the PDF in smaller ones?