[Snake]

With Green Gloves and Green Soles:


Without Green Gloves and Green Soles:


Fighting monsters on the same amount/level in the same dungeon floor.
The Green Gloves/Green Soles setup is behaving like ''-20% total exp gained'', instead of ''+20% total exp gained''.

[Neus]

Doubtful, otherwise every EXP boost would be busted. Is it possible your Aptitude is different in these battles?

[Snake]

In both, Lamii (White Tigress) had 42 aptitude. But when I get home I'll try to test again with another character in an arena match.

[Esther]

You're Lv. 21 during the first battle and Lv. 22 during the second, if that makes any difference.

[Fern]

Can confirm there's something odd. With the same amount of monsters, same level (player and enemy-wise):

148721 EXP
133848 EXP with green gloves
89233 EXP with 36 APT and green gloves

[Exxy]

Could it be that Aptitude and the gloves/boots don't stack? Granted this doesn't quite explain Fern's 80k example, not really sure.