The SystemWeaver ribbon menu groups are dynamic. The button label(s) may not be displaying because there is not enough room on the ribbon due to the number of currently displaying buttons and ribbon groups. You can confirm if lack of room is the problem by resizing your client wide, across two monitors. The labels will appear once you stretch it far enough. 

One solution is to hide buttons when not used by incorporating hideIfDisabled="true" where is it possible. This way, space will become available, and the labels will likely display more often. Alternatively, instruct users to hover over the button(s) to see the name.