Why cant I reroll 3 different RUNES into another random RUNE?

I used to be able to reroll 3 different runes into a random one before the patch. Now I can only upgrade the rune (3x lesser runes into a bigger rune of same type)

Currently I am only interested only in Resistance+Iron runes. Other types are useless to me.

Why cant I reroll 3x useless runes into potentially useful rune like i used to be able before patch???