Does indeed sound like textbook ' Rollback'.
Well known problem familiar to all 146 operator's which I thought had been 'modded' out at this stage. When we were operating them we had a FL260 limitation to avoid the issue, but there have been several reported incidents of the same happening. The tech guru's can correct me but I beleive the icing occurs somehwhere behind the first stage fan and can affect all 4 donkey's at the same time
