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It will not happen in Unity 2018.2.18....

Thank you very much!!!!I will track the report!

don't  need to add the component of the machine...just input bolt...

If I delete the Bolt folder.It become normal....I tried this on three different computers and unity 2018.3.2~2018.3.13......New a project--->input Bolt--->create a particle system--->give a standard shader to the particle system-->adjust the material value-->just stuck...

Thank you for your reply,I just input the Bolt from asset store in a new project and did nothing...It will get stuck when I adjust the standard shader....

oh...I used the wrong ID when I post the topic....

Now this is my correct ID...