Hi there
The reason the basic loop delays by 1 beat before you hear anything even though both loops start together, is that the initial cue from the bass loop starting is missed by the basic loop which starts at the same time: the sync :bass command is not set up when the first :bass cue is sent, so that it is the second pass of the bass loop which allows the basic loop to proceed, when the second cue is sent and picked up by the sync :bass line.
There has been much discussion about this in this thread if you want to look into it further