I wish I had seen this earlier. I did a date change on a Flex ticket and didn't notice (didn't even think to check) that the Flex ticket would be re-ticketed as a Saver ticket (they still charged me an increase fare for the date change in addition to the change fee).

I only noticed this after flying the sector and seeing only half the miles get credited.

I am now attempting to get this fixed and get the miles credited so we'll see.