I had the same. First it was a fuse inside of the shutter motor controller box (it was told so by the Polish engineers).
Now I have the same again, but the reason for this errors are the slip ring power transmission. If you rotate the dome then you can see the shutter power LED flickering. If the dome stops at a position without power then there is no connection to the slave - no connection by missing power. I have written a small script (work around). It is looking for connection. If there is no connection then the dome will be rotated by a fraction of a second. If it is connection then I am controlling the shutter. If not, then I am rotating the dome again ... and so on. The second way was to add a buffer battery inside of the moving part of the dome.
But this is not the way how it should work. Therefore we (including our lawyer) hope to get a repair by our local dealer.
The last way of operating the dome is to setup a much smaller controller by our own. It's much faster and more easy than to debug the arduino controller.
For shutter control we would do it at home position only including an inductive coupler without any mechanical contact. This is easy and save in operation.
Additionally the optical home sensor (sensitive to bugs and dust) must be exchanged to a reed contact.

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