There is an issue I remember
that if you were using a High Resolution screen (e.g. 4K), and Windows was upscaled (e.g. to 125%), then the sun study video ended up being completely black (issue #250854 & #66536). It is not the exact same result, but it is possible that you have a problem with upscaling, only you do not get a black video, but an empty one.
Could you check whether you have any kind of scaling applied in the windows display settings? (Start > Settings > System > Display > Scale and Layout)
If so, then please turn it back to 100%, restart the computer, and then try saving the video again.
If that wasn't it, then maybe the video coding component of ARCHICAD is broken on your computer. Try completely removing ARCHICAD from your computer, get a new installer from graphisoft.com (to make sure your installer is not broken either), and try reinstalling it.
Let me know if this helped. If not, we will need to look for the solution elsewhere.
Daniel Alexander Kovacs
Technical Support Engineer
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