排查：
- 被其他render mode 的UI或者canvas遮挡了，关闭掉其他所有的canvas看下
- You have to select a camera, in "Canvas < Render Mode < Event Camera"
- If its not the case also try removing check on Graphic Raycaster > Ingore Reversed Graphics on WorldSpace Canvas which worked for me.
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Check your Canvas. If your UI is in World Space have you specified the proper Camera?
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Does the UI component with your canvas attached also have an enabled Graphic Raycaster attached? If you add UI components via the GameObject menu this will be done for you, it is not if you use Add Component from the inspector. If not you can add one via Add Component > Event > Graphic Raycaster.
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Double check your camera. Is it the correct one?
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Does your Graphic Raycaster have any new Blocking Objects/Masks specified. Does it work if you disable them?
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Check your Canvas's scale. Is it negative? If so, is your Graphic Raycaster set to Ignore Reversed Graphics?
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Check your hierarchy. Are their objects above the one you are attempting to click that might be capturing the Click or other event?
https://answers.unity.com/questions/941790/world-space-unityui-buttons.html
https://forum.unity.com/threads/gui-button-doesnt-work-in-world-space.265048/