After setting up my Win 10 x64 Home yesterday for the purpose of repairing an issue with networking I wanted to start installing programs using some ISOs I have. The old double-click didn't work, instead I got "You don't have the permission to mount this file.". So I tried renaming it, checked if it was parsed (it wasn't), checked if I had any USBs plugged in (unless I'm blind there were none), downloaded VirtualCloneDrive (which froze when it got to "installing drivers") and went to bed, crying myself to sleep over yet another Win 10 ****up.

Fresh enthusiasm made it work this morning with the following fix.
Let me explain the peculiarities. I have an SSD and a HDD. The SSD was formatted throughout the re-install while the HDD with all my data was untouched. Possibly maybe this might have messed up some stuff. Dragged the ISO over to the SSD where my Win installation is but no success.
So I right-clicked on my HDD, Properties, Security - "Edit" and gave "Users", "Administrators" and "System" full control if they didn't already have it. The little wheels were turning and after the new rules were applied to new files I double-clicked on the ISO again and it mounted it. No questions asked.

Hope this will solve the issue for some of you.