Errors while signing PDFs created with Adobe Acrobat Pro

Hi,

I work for a company where we prepare to be signed dozens of documents, and the process has always been the same, smoothless. However, since I got last Adobe Acrobat Pro (version 2022.003.20322), users who try to sign using the signature fields sometimes get the error in the image. Other times, it's something about a HTF problem (I don't know what HTF is). I can't see a pattern; sometimes it happens, to some users but not to others; sometimes it doesn't.

We use Office 365, so the process involves saving the document as PDF (better that exporting, because it takes much longer, I don't know if that may be the key), adding the signature fields and then saving the PDF as other >> reader extended PDF >> enable more tools. As I said, my colleagues and I never had any problem until a few weeks ago.

I have to mention that signers are using Reader to open and sign the document, could it be the Reader version? That would explain why it happens to some people but not all of them.

Last time it happened, I tried to export it to PDF from LibreOffice instead of Word Office 365. Oddly enough, that worked...

I would appreciate if anybody knows what is happening here.

Thank you very much!