Seems like self.confirmCameraPrepTimeline is nil / was not initialized via function
https://github.com/esoui/esoui/blob/...pion.lua#L1581 properly before then
Do you try to open the CP scene via addon code or manually (keybnd/menu click)?
Maybe you try to open it wrong like SCENE_MANAGER:ShowScene .... (if even able per addon!) and thus the stuff is not initialized properly