Problems with Show/Hide on checked pages

I have trouble choosing which pages/posts widgets should appear on. The selection field is not usable. It looks like this:

I also can’t choose on existing widgets. The choice is locked. It looks like this:

I am using WordPress 6.3.1 and Widget Options 3.9.6. and PHP 7.4.

I hope you can help.

The page I need help with: [log in to see the link]

 

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