PDF modification detected- illustrator losing the changes and doesnt save open PDFS correctly

hello. I have had this problem for a month now, have been super irritating. I have read the forum about it and most people are just irritated about it and move on, for me illustrator doesnt save any changes if i continue to the editability, and if i keep changes, cant edit enything or see things from outside the board.
I am not modyfying the files anyhow, last time i opened the file was also illustrator. HELP, i keep losing my changes while working on pdfs.
