PDF will not open from a specific subfolder

Hello,

I made a scan of something and then saved it as a PDF on my laptop in a subfolder.
The strange thing now is that I can no longer open it from this specific subfolder.
If I save the PDF in a subfolder higher up, I can open it. I then tried this with other PDF's that are also stored in these kinds of levels of subfolders and they also did not want to open. But if I placed them in a subfolder higher up, I can open them...
Anyone have an idea what the reason could be?