Preview fails to save pdf forms
Solution 1:
If you open the link in Safari, you can do a Save As and the pdf is copied wherever you tell it to copy. You can then reopen the file with Preview and it worked fine for me.
If you can't get it to save as a pdf, go to the print command and when the print window opens there is an option on the bottom left to print file to a pdf. This will create a new pdf file.