Mars is never getting the terraforming candidate modifier in my games.

Long story short: I have yet to see a terraforming candidate Mars. I've started a good bunch of games since 1.6 came out (currently at 1.6.1), but never once have I seen the modifier, neither when I played a human empire nor when I encountered Sol as another. There are other (albeit really, really rare) planets across the galaxy where I've found the modifier after surveying an anomaly, but never Mars. When I survey it, the planet remains just as barren as before, with no popup showing up.

Usually I play with mods enabled, Unbiased Systems and Unique Systems Spawn 100% probably being the most relevant ones, but the issue is still there even when I turn all mods off. What bugs (haha.) me most is that apparently nobody else seems to have this problem, at least I haven't found any complaints on the forums, let alone here on reddit, so there isn't even another mod to fix it. What could I do about this?

EDIT: Typos.