I should also mention when haste is near to expire, if I cast expeditious retreat fresh while still under the effects of haste, it's completely canceled out and the move speed does not persist from ex. retreat. I suspect this is either intentional or an unintentional conflict of two move speeds not counting as different spells, or just not applying at all due to haste being active.
Anyway sorry for turning this into a general bug thread but I'll confirm your bug later Servant.