Normally it should be possible to drag on the timeline so that you can
select an area which you then can loop:
Other than that you should check what mouse modifier you have set up for doing a timeline selection. I set it up so that I can
Ctrl+Right drag to do a selection directly on items:
... which can behave like this:
And you can also left drag under the last track, which makes a timeline selection:
I hope this helps. (=