Not sure if the problem is in the doc or in the code.
Using Ardour 4.7 on Fedora 23 (installed via the Fedora RPM)
To move multiple markers, I have to Shift select them.
It is consistent with the overall keyboard feature: http://manual.ardour.org/ardours-interface/basic-gui-operations/selection-techniques/
But the documentation states that Ctrl-clic should be used:
- http://manual.ardour.org/working-with-markers/moving-markers/
- https://community.ardour.org/manual/moving_markers