Interpolation fails when 4-D auxilliary (but not derived) coordinates need transposing

In Gridded->ungridded the gridded dataset is sometimes transposed to move the vertical dimension to the outer-most (last) dimension. Associated 4D derived coordinates (e.g. air pressure) are automatically updated but auxilliary coordinates are just remaped - this causes an index loop up error when applying the vertical interpolation:
"
....
    hybrid_indices = [self.indices[i] for i in hybrid_interp_dims]
IndexError: list index out of range
"

One fix would be to look for these Aux coords and transpose them too, otherwise we'd have to apply some operation to the indices