Adobe Acrobat Reader DC

Hello, I have used Adobe Acrobat Reader for years, for marking up cookbooks (inserting new text, deleting text, adding sticky notes, marking-up text, etc) and it's worked great until now. When i insert new word with a space either directly before of after the new word, and save it, if i then check back to the comment, the inserted space(s) before/after word has gone (is not showing/deleted). Why is this? It always used to show as a space in the comments/mark-up box and now, suddenly, it doesn't - does anyone know why this has suddenly started happening, and can this be resolved, or will the recipient still be able to see the inserted spaces when they take in changes?