The Encryption Constant does not change when moved to Pokémon HOME, that is incorrect.
Keep in mind that it's EC mod 100 = 0 when the EC is converted to Decimal. In Hexadecimal, it's EC mod 64 = 0
Either your math was incorrect, or PKSM's was.
Also, if you cloned them in Gen 2, and then sent them up, they'd all receive new/different ECs, each with a 1/100 chance to be eligible to evolve to 3-Segment, if you only cloned 1 box, (20 pokemon), then you'd only have a 18.21% chance of finding one that evolves to 3-Segment.
If you cloned them AFTER they had already been sent to Bank, then the EC would be identical for the entire box you cloned, so there's no chance for any of them to evolve into 3-Segment. You'd have just copied the exact same set of ECs, all of which already didn't evolve into 3-Segment.