Tabs generated in MakerCam do not show up in Groundcontrol

[Gero]

This could be a clue also:
https://forum.shapeoko.com/viewtopic.php?f=33&t=1229

If I compare the post to the screenshot, this could be reason you end up with a 0.5mm tab that will hardly be cut, instead of a 5mm heigh tab.