Up until recently Redux used to apply its "number of videos per row" setting to channel page which was actually unintended behavior since the setting was supposed to be applied to homepage only. One of the recent YouTube updates changed the channel page's HTML structure and the Redux setting had to be fixed leaving channel page videos limited to 4 per row. It may no longer be possible to fix it via CSS only and some scripting might be needed to move video grid items between elements.
Up until recently Redux used to apply its "number of videos per row" setting to channel page which was actually unintended behavior since the setting was supposed to be applied to homepage only. One of the recent YouTube updates changed the channel page's HTML structure and the Redux setting had to be fixed leaving channel page videos limited to 4 per row. It may no longer be possible to fix it via CSS only and some scripting might be needed to move video grid items between elements.
Old behavior shown in https://github.com/omnidevZero/YouTubeRedux/issues/89