QtCreator clang code model error

Hello,

I am not getting any completion or anything.
The relevant errors when enabling logging seems to be :

error: retain documentation comments from system headers in the AST was disabled in PCH file but is currently enabled
error: PCH file was compiled for the target 'x86_64-pc-linux-gnu' but the current translation unit is being compiled for target 'x86_64-unknown-linux-gnu'

I have looked in all my kits but could not find a reference to "pc" or "unknown" - compiler ABI is x86-linux-generic-elf-64bit (the clang that comes with my distribution basically).

I have tried enabling / disabling PCH in the Code Model settings but it does not change anything (restarted in-between).