You can use Pumkln tools to reset your pose stuck pose to Tpose in the pose editor. This happens to me frequently and this tool is a life saver.
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Releases · rurre/PumkinsAvatarTools
A toolbox for easily setting up VRChat avatars in Unity. Adds functionality to the editor and automates some of the tedious tasks. - Releases · rurre/PumkinsAvatarTools
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