Hi,
I had to set a folder to [WindowsVolume] at the start of the installer to avoid issues with the installer not being able to reach a Network location. A workaround I found in this forum using a custom action (viewtopic.php?f=5&t=22880#p57479). This works fine when installing parallel or when uninstalling through Apps & Features. If the user chooses to replace an old installation when installing a later version the error for a unreachable network location pops up again (with the default value I defined for the Property as the path).
It seems like the custom action to set the path is not called during the process of uninstalling.
I added a screenshot of the custom action just in case.