Have a user who has directed pick and putaways turned off, all default bins for items turned off, Default Bin Selection on Item Card set to Fixed, the help for this field says "
Fixed indicates that items will be assigned a default bin which will not change.
If Default Bin is turned off for the item then where will it be getting the fixed bin location from ?.
Go to the locations list, by typing “locations” in the search function, then open the location card page for the location you want
to make changes to. I think those are the two options you should look at.