Save PDF form as read only is not working

Hello,

I've saved several PDFs as read-only (https://community.adobe.com/t5/acrobat-discussions/save-pdf-form-as-read-only-copy-using-fill-amp-sign/m-p/11944121#:~:text=1%20Fill%20the%20form%20and%20add%20the%20signature.,radio%20button%20for%20%E2%80%9CSave%20as%20a%20read-only%20copy%E2%80%9D.) with no issues. When I have a PDF that is over 100 pages or so, the progress bar makes it half way and permanently freezes. This is incredibly frusturating. How can I save the a longer PDF as read-only? I am on Adobe Acrobat Standard DC Version 2022.001.20117.

Thanks in advance,

Brian