At least, on Armor and Gloves they are.

I was testing out some stuff last night for my partner by upgrading a Daedric armor to Legendary and beyond with the highest Enchanted gear *not the Alchemy loop exploit* only to find i could not do this due to my Fortify Smithing enchantments being bugged... The Enchantments seem to work on my ring and necklace, and using a Fortify Smithing potion is fine too *did not try an Alchemy made Fortify Smithing potion though, just a shop one* but as soon as i put on either one or both the armor and gloves, my armor rating if i was to upgrade it dropped by 100+......
If i was to upgrade the Daedric piece with no boosts, it would end up Legendary ar180, with the ring and glove and potion, about ar225 i believe, but with the armor and glove on? Below ar110....

This never was a problem before the last patch, and i believe i noticed the exact same effect with Fortify Alchemy Enchantments aswell, atleast other people have also been complaining about it. I thought it was something to do with it going past 100% fortify at first, but that does not seem to be the case, and really, does not even matter, so its obvious it is a bug.

Anyone else having this problem?

Link to someone else having the same issues: http://www.neoseeker.com/forums/52479/t1699435-alchemy-enchanting-loop-broken-bugged-revised/

I am an avid enchanter and have had no problems whatsoever with the fortify enchantments. Will pay more attention. Since I am maxed out at 100 Smithing, I have no need to be using fortify smith on anything...

I went and tried it with my Orc, seems fine. He has 100 Smithing & Enchanting

All +Smithing gear, Orcish greatsword goes to 111, with +50 potion it goes to 137
Only necklace and ring +Smithing gear, it goes to 96, with +50 potion it goes to 121.

Maybe my old save is corrupted? I dont know, but many others are having the same issues. I tried making new armor/glove but it still did the same thing, instead of increasing it by that +% it seems to be -%...

Update: Turns out my BF is having the exact same issues as me with armor and glove enchantments not working correctly aswell, and detracting % instead of adding %...