PDF loses search function after adding note and saving

I have a PDF file, where no matter how many times I redownload it, if I add a note and save the pdf in preview, I lose the ability to search the PDF.

How do I fix this?

Or what is another good PDF annotator?

 

I also realized that I can no longer copy and paste when this is happening.

I download a PDF. I can search. I can copy text and paste it somewhere else. It works perfectly.

I annotate it. I save my annotations. Close out.

When I open it back up, I can no longer search. When I copy something to paste somewhere else, nothing pastes. I cannot even copy and paste into the search bar of that same preview window.

I don't know why this is happening! Please help