Tactix Delta: Only half of the watch is displayed

Does anyone have the same problem?

Sometimes the whole display is there but ususally only half of the watch face is displayed. If I am in an other screen everything is fine. So it is not a hardware problem. Also if I press a button the whole watch is displayed again, but only for some seconds.

I have not downloaded special watch faces or any apps. I have reset the watch several times and I have the software version 6.10 on my watch. Nothing helped so far. I have contacted Garmin service and they told me to send back the watch. The problem is. I need it right now and still hope for an update, because this looks like software bug. 

What do you think?