AEM component not appearing in list of component group in Design mode

Hi,

We have running a sort of weird problem on our AEM Instance. Some of the Components are not appearing in Component group in Design mode, but when you open the page that has already been authored with the component not appearing in list, then it starts showing up in Design mode. However, it still doesn't appear in side panel of component list. We have this issue in only one environment and it seems to work fine on others

Do any one has faced similar issues in past.