Blank PDF on some computers

I've generate some PDF invoices using a template as a background (also a PDF generated using Word). In some computers the fields doesn't get writen, they show an empty template. On other computers the PDF is generated correctly. The PDF files generated on both machines are the same size, but one has the fields rendered correctly and on the other appear blank, the info of the fields is on the file but written differently (inside). Sometimes an empty PDF is generated on computers with outdated browsers or OS, and sometimes on computers with browsers and OSes up to date. When a header is added, the text in the header is always writen, but the fields don't. I'm missing something? The template must have some requirements?
In mobile, the PDF is rendered correctly if viewed on safari browser or chrome browser for example, but empty on gmail app browser, or in other pdf viewers.