Dark patches in Capture's preview pane (top-down map of the site) can develop for a number of reasons.
However, they all mean that the camera could not pick up any depth information from that point.
Area is Obstructed or Not in View
The Matterport camera cannot see behind obstacles, so it paints black areas that it can't see.
For example, in the middle red box in the image above, the camera cannot see past the couch's "shadow".
In addition, the camera cannot see directly above or below itself. This explains the dark ring around the camera (top red box in above image).
Area is Out of Range
The Matterport Pro and Pro2 3D Camera has a maximum range of about 30 ft (10 m), depending on the environmental conditions.
Anything beyond that range will not reflect the infrared light the camera uses to sense depth data, and will just appear as black. This is especially common outdoors or in large empty spaces.
For example, see the bottom red box in the image above.
Area is Very Bright
The Matterport Pro and Pro2 3D Camera uses infrared light to sense 3D depth data.
Bright light (especially sunlight) can show up as black when scanning because it contains a lot of infrared light that "washes out" what the camera can see.
Avoid direct sunlight by closing drapes/blinds, or by scanning at less sunny times. Learn more.