Hello,
This is the answer I got when I asked the developers about this.
"There can be two reasons. There is no way to know why the user is getting the error, but the first one is the most likely cause:
If the user does not have a project that is compiled in a separate build directory, you will not be able to compile it if it is not on your own hard drive. This is due to a check that was incorrectly added within the separate build folder framework (P1TOOL-1099 Separate Build Folder).
The second reason is if the user has a project that compiles in separate build directory. In that case, the setting needs to be updated so that the build directory is on the hard drive."
This will be reported as a bug.