So, my character doesn't really use enchanting, so I thought I'd take all the fortify enchanting potions I've found and use them to give my current set of armor some nice buff enchantments. After drinking all my potions, I set about enchanting, and found that my enchantments were barely boosted at all, and my active effects screen only listed one of the potions as active.

PLEASE NOTE: I am well aware that drinking a bunch of "Enchanter's potions" will not stack. However, I have in the past been able to stack by drinking different strength potions (e.g: an Enchanter's Philter, an Enchanter's Draught, and an Enchanter's Potion).

My question is if anybody has witnessed this as well, and if this is due to a patch or if there's just something screwy going on in my game.

I don't think they ever stacked for potions, basically just doing the process of making a potion to improve enchanting, enchant alchemy on the item, then making another potion for enchantment after you have used your newer more powerful enchanted equipped. Then repeat.

potion for enchanting
drink potion.
enchant items for improving alchemy
make stronger potion for enchanting with new items
rinse and repeat.