Mage Armor is now only giving me +2 to AC. I tried it as a spell and a potion with two different characters and had the same effect.

Were you wearing leather armor?

Currently, when I cast Mage Armor it gives me +4 AC for about 15-50 (checked it twice, with different characters) seconds, and then gets back to its original value. Both instances I was wearing tunics.

The duration sounds broken; Mage Armor is only supposed to bring your total Armor AC bonus to 4 (so if you have leather, which is already 2 Armor AC, you only get +2 from Mage Armor).

The original Mage Armor change notes didn't mention this, but it was buggy (giving +5 AC to people wearing magical fullplate) so I fixed it.

I just wonder, when you wear, say leather armor, it gives +2 as suppposed, but when you take off the armor, it drops by two, still only giving +2 when it NOW should give a +4 in total. Is that intentional?

You shouldn't even have the +2 when you take off the armor you were wearing; Mage Armor is applied to a currently equipped suit of armor to prevent exploitation (otherwise, you could cast it on yourself naked, put on fullplate, and still have +4 AC from Mage Armor).

One of the characters was a monk, the other a wizard. Neither in armor.

Did your clothing have any armor AC bonuses, maybe vs. alignments or races?

Monk habit +1 AC(Armor Modifier) Enchanters robe on the wizard AC 0

Previously I got an armor bonus of four from mage armor,

As of today, I now only get 3. My robes have a +1 modifier, but that modifier is ignored, and a +3 is respected instead.

The engine only uses the highest modifier, so +1 and +3 still only equals +3...

Tried it with yet another monk, wearing +1 AC habit. Still only 2 AC with a Sennick.

Alright, I just tried this with leathers +1 (Total of 3 armor AC) It gave me no AC, i examined my armor and it gave it another +1 (Temporary) But the + AC doesn't stack.

Are these all straight +1 AC armors, or are they AC vs. ...?

They are all straight +1 AC.