I read your response again (need to read before posting
The problem is that each bar is not an even number of samples so the BAR lines are sort of rounded to numbers of samples that make sense.
Your samples need to start exactly on the bar, but it's as if you had 44100 divisions of MIDI and you needed to round them to your tempo. There would have to be gaps to do this.
Another way to think of this is that each "bar" that you have is not the same number of samples. Some bars will be slightly longer depending on the number of samples that will fit in the resolution.