The seems to be an issue with QtCreator detecting custom QML modules. I have found that sometimes when adding a custom QML module, QtCreator will not recognize the import, and present the inline error message "QML module not found".
However, if everything is done correctly the program will still function as expected at runtime, meaning that this error message is incorrect. This can of course be quite problematic when developing as it leads one to think there is a problem with an implementation when there really is not.
I have attached a sample program which displays this problem.