Brute force protection whitelist not working

Our NC is behind a F5 proxy and therefor all traffic to NC seems to be coming from a single IP address.
We have installed the Brute Force app and we added the ip address from our F5 to the whitelist.
Yet the ip still gets blocked.

Any ideas what could be causing this and how to resolve?

{"reqId":"mzES08q1MRa55cakm244","level":1,"time":"2020-03-20T14:16:11+00:00","remoteAddr":"","user":"--","app":"core","method":"POST","url":"/index.php/s/EEmQYxRScdwB2Sd/authenticate/showShare","message":"Bruteforce attempt from \"\" detected for action \"publicLinkAuth\".","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.132 Safari/537.36","version":"","id":"5e75173d88bbc"}

Nextcloud version: 18.02
Brute Force App version: 1.5.0
Operating system and version: Ubuntu 18.04.4 LTS
Apache or nginx version : Apache/2.4.29 (Ubuntu)
PHP version : PHP 7.2.24-0ubuntu0.18.04.3 (cli)

Have you cleared the brute force blocking table before you whitelisted the ip address? Otherwise it might be possible that the address is blocked until it will automatically be removed from the list after some time.