Hey I found out the issue. I installed Mattermost with mattermost-omnibus and I found a section of the documentation that states this:
For Omnibus to work properly, there are some configuration parameters that are fixed and cannot be changed through the web interface - for example, the port that Mattermost uses to run. Other parameters need to be configured directly in the
mmomni.ymlfile instead of in the Mattermost web interface or theconfig.jsonfile.
Issue resolved!