Yes, CH LENGTH is a very important parameter here. The manual entry on it barely makes sense to a native English speaker.
CH.LEN controls for how long the active pattern will play before a cued or chained pattern will begin to play. This setting is important when, for example, M.LEN is set to INF. If no CH.LEN setting is made, the pattern will play infinitely, and the next pattern will thus not be cued. But if CH.LEN, for instance, is set to 64, the pattern will behave like a pattern consisting of 64 steps in terms of cueing and chaining.
I mean it makes sense, but took me about 25 times to get it