It shouldn´t matter. I ahve experienced the same. For all intends and purposes, the game recognize you as drow after Adalons spell. See it as a cosmetic and RP feature. Maybe you have installed bg2 tweak pack and unintentionally installed the option to not change avatars into drow?
Okami
Member Posts: 312
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https://forums.beamdog.com/discussion/61898/tressets-choice-tweaks
While it does not change your avatar, it gives you drow portraits while in the Underdark and thus adds to the illusion here.