question

This is a similar issue to the other one you asked. Your distance between rate change points is exactly 0.1, i.e. the length of a bottle. There is probably a floating point precision issue where sometimes it's determining that the 'chunk' is wide enough to draw a full bottle, and in other cases it's not wide enough. Since the chunk width is exactly the width of a single bottle, the math will end up falling on one side of a comparison in one case, and on a different side of a comparison in another. This is the nature of computers doing floating point calculations.

While we could probably do something to mitigate this, in the end, as I said in the other answer, I don't think you're building your model right. You should avoid chunking as much as possible.

See my other answer:

https://answers.flexsim.com/questions/135865/unable-to-set-number-of-units-in-mass-flow-conveyo.html