It is still an Interim report and it states that ice PROBABLY contributed to the reduction in engine thrust. The AAIB is still not prepared to state definitively the cause of the accident.
I still suspect that it was a programming error in the engine management software. A combination of events during the descent, the hold and the final approach produced an event that did not figure in the long list of IF/THEN statements that control how the engines operate in any given scenario.
Flame me if you like but I maintain that, if it was ice, then the problem would have surfaced long before now.