The reason the sequences change instantly is so you can switch rapidly between them mid-sequence, to make the music sound more interesting than just playing one loop after another. It’s definitely intentional – it isn’t everyone’s cup of tea I agree, but it can lead to more interesting music.
If you want one sequence to run after another one perfectly you can add it to the end of the other sequence by dragging on top of the first one. Or, if you want to play it live, I recommend switching sequences just before the end of the sequence so you catch the first beat.
Maybe one day in the future I will change how this works, but please don’t ask me if you’ve read this, I’ve answered this question 100 times.