ProjectExplorer truncates "Source Files" filepaths

In the project explorer sidebar, under "Source File" file paths miss their first character as shown in the attachment (and below). Double-clicking on the file results in a "file error, path not found" message. Compiling works fine however.

In CMakeLists.txt these are defined as, and shown in project explorer as:

${PROJECT_SOURCE_DIR}/src/main.cpp ---> P:\rc\main.cpp ("src" is truncated)

Printing the CMAKE variable using MESSAGE shows no truncation.

When a full path is supplied in CMakeLists.txt, the issue does not occur, i.e:
C:\sourcedir\src\main.cpp ---> C:\sourcedir\src\main.cpp (CORRECT)
Given cross-platform development I prefer the former setup.

Best guess:
The treelist path generator expected a double dash in the drivename (i.e. "C:\ \"
), got "C:\" and truncates the path string instead. Using a VM shared folder may contribute.