Forage Harvester makes chaff in radon trailer disappear when it collects grass.

[Snaril]

So I have the platinum expansion for FS19 and when using the jaguar forage harvester with the radon sugar cane trailer I can collect chaff from grain fields using the direct disc. But as soon as I finish a line on the field and I get one liter of grass, all the chaff in the trailer is replaced with however much grass I've harvested. I'm not sure how to avoid this other than painting the edges of my fields so grass doesn't grow on the edges. Seems like a horrible bug to have some 60000l of chaff for it to be replaced by 53l of grass...