Yeah, but, the downloaded .part file is exactly the same size as the same (original) file if I download by right clicking and doing "Save link as..."
To explain that using the manual from the thread mentioned here on the forum:
If I directly click the link, I get the .part file and it is 3,174 KB in size. Remove .part from filename and file opens without problems as a pdf file.
If I right click and save file as, the file is 3,174 KB, has the correct file name ending in .pdf
I'm using Firefox on a Win 10 PC, will go and check if it happens in other browsers.