This can sometimes happen when there are multiple Component components in the definition being solved simultaneously. Somehow the Tekla Structures API gets overwhelmed and can ignore the class altogether for some of the inserted connections.
From your pic alone I’m not sure if that’s the case here, or if there’s something else going on.
If you re-trigger the component (e.g. double-click the component name), do the class get fixed?
One option is to turn off ‘Run in background’ for all the Component components (right click the component name > untick ‘Run in background’), that should fix things. You will need to do this for every Component component in the definition.