to expand on this, I spent 10 days of straight attempts, so that's 30 tries total and I _still_ didn't get it. This goes beyond bad RNG.
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Sorry to hear that, but we tested this before the release and it worked as intended on our end.
As mentioned above, it's likely that the prerequisite for the Iris ending simply hasn't been fulfilled yet, but there's a low (but not zero) chance of bad RNG, too.
During testing when we had only Leyla's, Emily's and the 'nobody' ending and the probability was 40% for Emily and 30% for each of the others, I got Leyla's 9 times, Emily's 3 times and the nobody ending zero times in my first 12 attempts. I doubted the RNG, too... but when we ran tests in the 100eds, it started to even out and give the expected probabilities.
It's possible that RenPy's RNG implementation is a bit 'clumpy' somehow, but we need to use it to ensure savegame compatibility.
We'll try to improve this in the next update and also add in-game hints if the Iris ending isn't reachable yet.