On JIRA 8.15.x, the Filter on the Test Repository/Test Plan Board isn't working properly

On Jira 8.15.x, when trying to use the Filter on a Test Repository/Test Plan Board, the following problems occur:

• on the Simple view, the Apply, Clear and Cancel buttons aren't displayed;
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• on the Advanced view, the JQL Search input area displays an error and the Apply, Clear and Cancel buttons aren't displayed;
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