Conan plugin is not flexible: if we have only release Conan packages versions then QtC configures only Release build for our application and Debug configuration is not possible - it errors on configuration and/or build step. However it is easily possible to combine Conan release packages and Debug application version for example if we want to debug only the application and not to dive into dependencies, or do not want to maintain/build debug packages repo.

While to build Debug version of application with Conan release packages just need to add single cmake argument on configuration and/or build step:

-DCMAKE_MAP_IMPORTED_CONFIG_DEBUG=Release

and 

-DCMAKE_BUILD_TYPE=Debug

works fine since then. More info could be found here:
https://github.com/conan-io/conan/issues/17390 

So I propose to add Debug build configuration as well even if only release packages are available. Thanks!

jsee FYI