Doesn't sound like a possible a reason for me. Conflict in the region has existed for some time, so place for photo cameras focusing was well known.
> is kept secret so as not to disclose surveillance capabilities.
It's not a news that we are being watched, so this reason also doesn't sound reasonable for me.
Any other reason? May they have something to hide?
As I understood many of the so called evidences are based on the youtube movies taken by the cell phones by random people. So that should not be a problem to fake such kind of evidences. Also treating google earth photos like an evidence sounds funny for me.
a) You cannot get high-resolution imagery from geostationary satellites. It comes from low earth orbit spacecraft.
These, by the very nature of their orbit, cannot remain fixed over one place; they move relative to the ground below and once past it, will not be back until they've completed an orbit.
This, then, means that someone will have to prioritize what areas to investigate and at what times; satellite orbits can be changed, but that is _extremely_ costly, as you need to expend fuel - and there's no simple way to refuel; spend it all, and you need to launch another satellite.
So - maybe the US found that something other than Russian-backed militias destabilizing Ukraine warranted their attention. Say, IS or al-Qaeda - and focussed their attention elsewhere.
b) It is not news that you are being watched.
It may, however, be news when a satellite is watching; perhaps the US piggybacks surveillance gear on commercial satellites, for instance - they couldn't reveal satellite imagery without anybody and his dog being able to figure out which satellite took the photo.
Or - the quality of the photos may be much better than anticipated.
Or, for that matter - maybe the US doesn't want to stick this to Russia as hard as they could; perhaps they do not want to find out what the world community would do once it is proven beyond any doubt that Russia gambled that they could destabilize Ukraine at no cost to themselves, only to find that the rebels and their -ahem- advisors of undisclosed origin promptly escalated the conflict by committing mass murder by incompetence, ignorance or both.
As for your last point, I don't quite catch it. Is the lack of obviously faked 'evidence' evidence that someone is having something to hide?
Publically and commercially available imaginary (google earth, DigitalGlobe, etc.) just couldn’t see anything.
They only sense some visible light, and/or near IR (a.k.a. short-wave infrared). You can view some specs there: https://www.digitalglobe.com/resources/satellite-information The clouds are completely opaque in those spectrum, so the land below clouds is completely invisible from those satellites. And the segment of the missile trail above the clouds is very volatile, there’re strong winds there.
Nothing can be seen on those images. And in the video uploaded by Netherlands’ public prosecution office, they told satellite imaginary between 16 and 21 of July is unusable, because clouds.
I'm not familiar with such kind of stuff, the point is - I'm sure they do have strong evidences but for some reason those evidences are not yet revealed.
The problem with that, no one except the US military and government knows for sure, whether they have far IR aka thermal imaging sensors on their satellites, or they don’t.
Fortunately, there’s a solid body of evidence even without that secret data.
It includes a lot of photos, videos, intercepted phone calls, and other related data. The video is official, meaning the investigation team has evidences backing every statement made.
a) Relevant coverage does not exist. (I find it unlikely that full real-time coverage of the globe is available.)
b) Coverage exists, but is kept secret so as not to disclose surveillance capabilities.