This is due to a bug that was supposedly fixed a long time ago, but as it turns out, it's still very much present: http://feedback.arma3.com/view.php?id=17602

As a temporary workaround, you can enable the debug console (Granted you're admin), and execute the following in the debug console, which will automatically remove empty groups each half minute (only execute it once):

• spawn

{

while { true } do
{
    {
        if (count units _x < 1) then
        {
            deleteGroup _x;
        };
    } forEach allGroups;
    sleep 30;
};

};

Thanks. Hopefully it will work.

I have the same exact issue in 1.30 :-/ I had to reconnect to the server to fix it on a temp basis.

I am hoping that what you mean, is the selection for OPFOR/BLUFOR/indep disappears.

I found that what causes this is that if you search for a unit that doesn't exist in a tab (ex: single units), then when there are no results, switch to another tab (ex, groups). This will cause the group to disappear from the original tab completely.

I've been working around this by using the remote control module then releasing, it seems to reload the interface and restore functionality.

To avoid, don't leave anything in the search box before you swap tabs.