Strange roast using Gene Cafe and some new beans

[NorthSouth]

I am have just started roasting a Rwanda Inzovu coffee using a Gene Cafe.
The temperature during the roast looked perfectly normal (according to the roaster display).
My problem is that the beans do not seem to have expanded properly and more chaff than usual is still sticking to the beans when the roast is finished.
Is this just this specific coffee?
Also started to roast a Tanzanian peaberry which didn't seem to expand very much either.

I will do a roast today with beans that I have previously roasted without issue.

Anyone got any ideas as to what might be going on?

Thanks

 

[peterjschmidt]

Could just be a dense hi-grown bean that doesn't accept heat as well as the beans you're used to, and didn't go as dark as you thought you did.

 

[NorthSouth]

Could just be a dense hi-grown bean that doesn't accept heat as well as the beans you're used to, and didn't go as dark as you thought you did.

Beans were plenty dark.
I roasted longer/darker than usual to try and get rid of the excessive chaff.
Caused a slight change, but nothing dramatic.
Definitely still dense and insufficiently expanded (my opinion) even after this.
Thanks

 

[sae]

a natural coffee will have a lot more chaff than a washed coffee.