Cannot find the pdf file in Dropbox after editing it using acrobat

As shown in the topic, I m not able to find the pdf file in Dropbox after editing it using adobe acrobat. I mean yes the edited pdf is still there, but when I search it with key words in Dropbox, it shows no result.

I know I can check one by one to find it at last but there are thousands of pdfs in the file beacause it is for company use. I have to use the 'search' function. This happened about 2-3 days ago. Pls fix it. Thank you.