I have found out a minor usability bug from v 11.0.5.26351.
Feature occurs if I output data from Join tool so that some or all left outputs are unselected:
Now when using the output of the left stream in another join there occurs a small bug affecting workflow:
In the rightmost join tool Alteryx does not recognize right away that there should be multiple columns, A, B and C coming from the left output. This can be solved by going out of the tool and getting back, but this has a minor impact on the workflow.