Well, there may be a twist to the tail...
Volvo call my gearbox an MPS6, exactly the same unit (identical) to my Kuga Powershift 6DCT450, same gearbox made by Getrag.
Ford and Volvo buy filters from IBS Filtran and put them in branded boxes.
I bough some "Volvo" filters, they appeared genuine in proper boxes etc, looked the same.
I've just bought 5 Ford filters (£22 each, local dealer wants £40 each!) and compaired one to my last "Volvo" filter.
The filter housing on Ford is Matt and much stiffer.
The filter cartridge ends are on Ford are shiny (matt on "Volvo").
Ford have a feint red line in the middle the filter cartridge medium.
The bypass valve on Ford is 1/3 rd as stiff as "Volvo" xxxxxx. Ford will bypass oil much easier in case of filter failure or blockage.
After taking a new "Volvo" filter to bits, the filter medium is supported by nylon mesh, Ford use stainless steel mesh to stop the filter collapsing.
So I've come to the conclusion I've been sold knock off Volvo filters!.
This wouldn't cause the entire problem but deffinitely some of them..