Greetings. That’s not a bug, its fully intended.
If you wanted to choose Sylvanas, you had to click a tiny-not-warned-at-all dialogue options BEFORE you clicked accept.
No GM is going to fix this for you. Devs forbid this. We joined our voices for this deception/mislead/bad programming/whateverisgoingtospoilmycharacterforever.
Please, if you care for this choice leave a reply and likes here:
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Join your voice to ours. We must make devs listen to us.