This crash is in the wild and has been reported by two users recently. EDIT: this post shows screenshots and logs for 8.13, see the subsequent reply for 8.14B1 /EDIT
Those threads may contain additional information and logs.
I can reproduce the crash (have done so in German and English UI):
Start Search, specifying Syntax search, opting for a new search (note: running saved searches seems to work fine for me as well as for one additional user who reported the crash):

the search builder window opens.
Add search components

When selecting Clause, the program will spin the cursor a bit and then crash.
Logs:
6014.Logos.zip
The error ID varies, but the text is consistent:
Error ID: 72
Error detail: XamlParseException: No matching constructor found on type 'LDLS4.Panels.SyntaxSearchPanel.SyntaxCheckboxControl'. You can use the Arguments or FactoryMethod directives to construct this type.
System.Windows.Markup.XamlParseException: No matching constructor found on type 'LDLS4.Panels.SyntaxSearchPanel.SyntaxCheckboxControl'. You can use the Arguments or FactoryMethod directives to construct this type. ---> System.MissingMethodException: Constructor on type 'LDLS4.Panels.SyntaxSearchPanel.SyntaxCheckboxControl' not found.