Not sure if it's been brought up before, but I've got reason to believe the Stealth Screen buff for a permanent 30% buff for cloak on planets isn't working, as I just had a rather good planet with the buff on it scanned. The scanner (fortunately from a friendly legion) admitted they had scan just over 13k, while the planet itself had nearly 17k cloak with the buff included. Either my understanding of how the scan/cloak system for planets is incorrect, or something isn't providing the cloak that it says it is.

It's not the buff itself, it's the whole cloak system at whole. All though even if something was fully cloaked.. There's always possibilities of detecting it.
At some point I scanned a planet with the 1 week long 50k cloak buff - that was half way through the week. My scan was below 4k at the time.

That planetary event was removed, for the exact reason you just mentioned, as it was faulty, hasn't been seen since.

Majority of my planets are all fully cloaked, and none have ever been scanned.