Editing Transfer Routines not all fields available for selection

Dear Experts,

We have recently upgraded our entire landscape to 3.5 from 3.10 Content. However we have now started doing some more development and have noticed a problem.

When displaying the existing Transfer Routines you can see all the fields available for selection. However as soon as you try to edit the routine or create a new one almost 1/3 of the fields are no longer listed for selection.

Any ideas ? I don't want to have to select all fields just to get the one I need!

Thanks in advance.

Craig