No valid kits found, even though there is one

Install Qt5.9.4 content from staging and both released QtCreator 4.5.1 and preview QtCreator 4.6.0-beta1. Launch preview creator and try to configure one of the existing examples or create new. No kits registered although gcc_64 binaries are installed.

Open 4.5.1 Creator and do the same, kit Qt5.9.4 gcc_64 is visible and project can be configured/created.