Ok with the Simulator, but not ok if you use a DMK 21AU618.
This occours on two different systems equipped wth this kind of camera.
A workaround could be to complete the procedure with Ekos, and then create externally the master darks and replace those bad build by Ekos, but it is not a great solution
This is not with simulator, these are using the images you supplied. There is a feature in CCD Simulator where it loads images from a certain directory. I used this feature for multiple sequences (1 sec, 2 sec, 500 sec..) with the same result.