External Sites Duplicate my sites

Situation: I am using Pico CMS to host a site using the Pico CMS plugin (everything works as expected). To facilitate navigation within Nextcloud, I thought of using External Sites plugin to link to the site on the navigation bar.

Problem 1: “Remove Site” removes a site on the page, but on refresh/navigating away, the site returns. What I did was to remove the site, and add a new site. So now I have two sites showing in the navigation bar – even though I deleted the first one earlier on.

Problem 2: After spamming the “Remove Site” button a few times, the sites suddenly decided to duplicate themselves. Now I have 4 sites showing in the navigation bar.

Problem 3: None of the sites are able to be removed as of now. So I had to disable the External sites plugin so the navigation bar will look “normal” again.

What I have tried 1: Deleting the whole External Sites folder and putting a new one in.

What happened 1: Nothing. The 4 sites are still there.

What I have tried 2: Tried looking for where the site information for stored.

What happened 2: I cannot seem to find the configuration file where it holds the site information (which I assume is going to be a JSON file).

Question: This may be a bug but can someone point me in the right direction as to how to remove the sites manually?

Additional information:
OS: Ubuntu 16.04.5 LTS Server edition
NC: 14
Web App: LAMP