What OS? What Desktop? X11 or Wayland?

What does that mean? Can you show us the issue. I'm going to open an account and just download the pdf file that comes with the account. Here is what I get from the site. I was able to open the pdf from the account and download it. see screenshots

Operating System: openSUSE Leap 15.6 KDE Plasma Version: 5.27.11 KDE Frameworks Version: 5.115.0 Qt Version: 5.15.12 Kernel Version: 6.4.0-150600.23.17-default (64-bit) Graphics Platform: X11 Processors: 16 × AMD Ryzen 7 PRO 6850HS with Radeon Graphics Memory: 62.1 GiB of RAM Graphics Processor: AMD Radeon Graphics Manufacturer: HP Product Name: HP EliteBook 865 16 inch G9 Notebook PC

I am using an updated version of Firefox. I have a Linux Mint 21.1 OS, which is up to date. My desktop is Cinnamon. Wayland isn't yet used on Cinnamon

https://9to5linux.com/linux-mint-21-3-to-ship-with-cinnamon-6-0-and-experimental-wayland-support

When I open pCloud and click on my PDFs, they open up for me. When I copy that link into a post on social media, so that others can read the study, it will not open in Firefox, but it will open in other browsers.

When I copy that link into a post on social media, so that others can read the study, it will not open in Firefox, but it will open in other browsers.

Again, you're telling us about the issue, but not providing evidence of it. Screenshots, links, and steps to replicate please...

I gave you all of the information. The fact remains that it is only Firefox that doesn't allow the PDFs to open. Other browsers allow them to open. You can see what my system is. You know pCloud. And you know that my PDFs don't open in a Firefox window. There is no message that something doesn't work. It just opens a blank tab and the PDF doesn't open.

Good luck. Jones out

Thanks for your quality effort.