The "mux 2" object does not expect a trigger to change it's output but rather something like a gate. It will output i1 as long as s = 0 and i2 while s = 1. So you'll probably acheive what you were going for by connecting the LFO output directly to the "mux 2" object.
If you ever have to convert a gate to a trigger, you can use "tiar/logic/rising" and if you need to lenghen a trigger signal to become a gate there's "timer/delayedpulseduration".
Have fun with the Axoloti and don't hesitate to ask more questions. Cheers!