Cannot rolls Attack Modifiers, rolled attack mods

I found a Karui Sceptre of Spellcraft in delve, used a Regal Orb to make it rare, it rolled added lightning damage to spells and still had Cannot Roll attack Modifiers.
I then used a Chaos Orb to reroll the stats, and ended up rolling two Attack Modifiers.



I know I didn't accidentally use another Chaos Orb because I made a mental note of having 511 before and now have 510.

To my knowledge this shouldn't be how this interacts, so I'm posting it in bug reports, however if I've missed an interaction (say meta-crafted mods only work once) I'd also be happy if that were indicated.

I recently used a Resonator with cannot change Prefixes mods and found out that meta crafting mods do not work with Essence or Delve crafting, however the orb I though for sure would work correctly.

Hello there.

A chaos orb rerolls all existing mods simulataneously, so the "of Spellcraft" suffix is basically not there anymore when the new mods are created, and so is its effect.
Such mod typically has a purpose when adding further mods on the item (augmentation, regal, exalted), mostly because the conditional mod remains on the item.
However, i believe it could have worked if you also had a "suffixes cannot be changed" on the item.