Wordpress - WAF 6G Bad Request


I run H5P on Wordpress. On my server, I enable WAF 6G. So far, the problem I encounter is the search box in the All H5P content 'fail to load data'. There is no problem when the WAF 6G is turned off. 

I have whitelisted H5P plugin, but the problem is not solved. I still got bad request error:  [":bad_request_7:"] edniche.study "GET /wp-admin/admin-ajax.php?action=h5p_contents&offset=0&limit=20&sortBy=4&sortDir=0&filters[0]=P1 HTTP/1.1" 403 "https://{site.com}/wp-admin/admin.php?page=h5p" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.135 Safari/537.36"

Could you advise on what I can do to solve the issue?

Best regards,

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