Upgrading Vells Heart

Is it possible to get different stats on your vells heart once you have rolled it once?
I have done multiple (8+) attempts using khans heart to upgrade my Vells heart, but it has not ONCE rolled a different stat from what it had before.
It has only rolled the top 5 stats shown on the picture. I have not once gotten Stun Ignore, Down attack dmg, and so on...
I have also attempted upgrading it with protection, and back to attack just to see if it would give me different stats, but I still got the same stats -> attack, accuracy, knockback ignore, knockdown ignore and catch ignore.
If this is intended, it seems dumb to need ANOTHER vells heart to get different stats. As this has cost me over 30 billion silver so far.

 

I agree with olafkk. Kindly fix this. It's not worth the silver and resources to upgrade this on its current status.

 

All rng, better stats mean lower chance to get. You need to reroll more.