These Ai suggestions are worth a try...
"Print to PDF (Flatten): Use your web browser to "Print" the problematic PDF to a new PDF file. This action will flatten the form fields, turning input into static content that is visible in all readers:
Open the file in a browser.
Select the print option.
Choose "Microsoft Print to PDF" or "Save as PDF" as the printer.
Save the new PDF and test it in Pico PDF.
Convert PDF format: Tools like online PDF/A converters can sometimes standardize the PDF, improving compatibility with different viewers
Tips
By flattening your completed PDF using the print-to-PDF method, you should be able to view all pages and content properly in NCH Pico PDF and other editors. This method is non-destructive and ensures you can access your filled form everywhere.
Always save a blank original copy before filling out forms for future use."