A serious Animation problem in 2018.3

after I updated to 2018.3 there is a serious problem in unity3d.
when I create a new animation clip in Animation window then unity3d doesn't work and I can't make my animation. I must End Task unity by Task Manager.
I was hoping this problem would be solved in the next updates but after two updates, it didn't.

please fix this. it's very necessary.

 

Have you submitted a bug-report for this issue? If you didn't, perhaps Unity Technologies isn't even aware of the issue, thus no fix available.

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