[BUG]: SignalingManager cant add item

[XiaoMinghui]

Package version

3.1.0-exp.6

Environment

* OS:Win 10
* Unity version:2021.3.15
* Graphics API:DX11
* Browser:Chrome

Steps To Reproduce

SignalingManager cant add item

Current Behavior

No response

Expected Behavior

No response

Anything else?

No response

[karasusan]

This issue was fixed.
#863