Help wanted with Cmake using multiple cmakelists

I’m experiencing problems using the cmake plugin.
When I try to build this software: https://build.snapcraft.io/user/OpenMapper/OpenMapperDesktop/57353

I get this error, though I do not understand why this path is used instead of the relative one as written in the main Cmakelists:

CMake Error at CMakeLists.txt:48 (INCLUDE):
include could not find load file:

/build/7a19a0ed1e9bb85076943c265d7698e4-xenial/parts/application/src/libs/OpenMapper/CMakeLists.txt

To the software: It should be a desktop app, the main CmakeLists includes the cmakelists of some libraries in the folder ./libs
This including of other cmakelists is not working.
The mentioned software can be found here: https://github.com/OpenMapper/OpenMapperDesktop