Quote Originally Posted by Athiril View Post
10% coverage is a LOT less than 90% coverage. And you need to agitate on as well as cycle, not just cycle.
Turning a Jobo 1510 upside down will not keep 90% of the film roll submerged if you fill the tank with the recommended 250ml. Unless you fill the tank to the brim with developer, I would strictly recommend against turning it upside down except for very short times during agitation, and for pouring out the developer, of course.

My conclusion from this disaster was that film is either completely submerged in or completely out of the developer, or it can be guaranteed that all parts of the film are submerged/out of the dev for the same total amount of time, like in a rotary processor.