I can't unfolding the tab

Maybe try re-setting preferences:

Have Premiere closed.

On Mac hold down shift/command/option and click on the Premiere icon to open it. Let your system make changes

Same procedure for Windows but hold down shift/control/alt.

Hope this helps

Hi Lost5D24,

Thanks for writing in.

What are your system specifications (CPU, GPU, RAM, OS)? Also, could you test it on a new project?

Please try resetting the preferences of Premiere Pro and see if it brings any change. Here's how: https://community.adobe.com/t5/premiere-pro/faq-how-to-reset-trash-preferences-in-premiere-pro/td-p/8236158 

Let us know if it helps.

Thanks.

Nishu