How do you get Ekos to take bias frames? My cameras, a Nikon D600, D5300, both have 1/4000 second shortest speed.

However when I try to set it for bias, Ekos shoots and 11 second exposure. I noticed if you hit the down arrow in the exposure box, it goes through a few settings, then jumps down to 1/25000 sec. None of the sub-second exposures work however, they just take an 11 second exposure, then re-open the shutter and then leaves it opened. I have to turn the camera off to close the shutter.

So how does one get Ekos to properly take bias frames?

Thanks.