I have been addicted to using Apple Books ever since I purchased my iPad. It is smooth and has a simple interface, unlike other apps. Most importantly, it fits perfectly with the Apple ecosystem. However, there are some bugs that have existed for a long time without being fixed. Among them, the most annoying and frustrating one, also the most persistent one, is that notes made on highlighted texts in PDF files usually get lost after the file is closed and reopened while the highlights remain. It happens most frequently (actually, almost certainly) to the notes at the beginning of those files, although I am not sure whether that is because they are in the beginning of the files or they are the earliest notes in the files because obviously I tend to read the files from the first pages to the last. I contacted Apple Support regarding this problem. After recording my complaint, the agent suggested a phone call with their staff member. However, I have serious phone anxiety, therefore I preferred communication via text or email, never via phone calls. The agent said that the only available way was through phone calls, therefore I gave up. I really appreciate this app, it helped me read so many books, for school and for fun. But the loss of notes really annoys me. Please fix this problem.