We have disabled "Directed put-away and pick" as it is a nightmare to manage the warehouse with, and simplifies things a lot better for the warehouse.
As our warehouse was using Bin Ranking before for picking we switched to alphanumeric ordering in our warehouse so this could be achieved.
However it wants to set a fixed bin to items? We do not need this!
Here is an example of a pick for an item it would select the product in P2.E not he one in P2.A (A being on the ground level and then we have racking B,C,D & E at the very top) so you want to pick from P2.A06

So going into the bin it has set the top level bin as the "default" and "fixed"
You uncheck these and it gives the error...
Validation Results