I'm not sure if it's legal to change the number of targets as part of such effects. Were you trying to do that?

@tool4ever Rules wise, you can't change the number of targets

So if you targeted 1 Player, you should be able to change the target.
If you targeted both player, then you should not be able too.

But maybe the issue is related to #5334 ?

@Hanmac

So if you targeted 1 Player, you should be able to change the target.
If you targeted both player, then you should not be able too.

I was in a four player EDH game and targeted two of the players with the original effect. For the copy effect I should be able to change the targets to whoever I want as long as I target two players, right?

In my own testing, Ulalek hasn't let me change the targets on numerous effects. With Ulamog, the Ceaseless Hunger, the copy's cast trigger doesn't do anything and doesn't let me pick new targets for removal--presumably because it's trying to target the same two permanents that just got exiled and coming up with nothing.

Ulalek doesn't seem to copy Spawn-Gang Commander's cast trigger either. It only creates three tokens total, with the copy creating no tokens.

For other effects, like Hideous Taskmaster, it actually has let me pick new targets for the copy. About 50% of the time it either won't let me pick new targets, or fails to copy the cast triggers at all.

This issue has not been updated in a while and has now been marked as stale. Stale messages will be auto closed.

Just tested the problematic cases for this issue, Kozilek, the Broken Reality and Ulamog, the Ceaseless Hunger, and they seem to be working fine now allowing me to change targets.

The two target case for Ulamog

The two target case for Kozilek

The single target case for Kozilek

However since my experience was that the transition between prompts of copies of a triggered ability from the same source is pretty abrupt, especially the times I only chose one target for Kozilek's cast trigger, it's my impression that the current state of affairs regarding how copied abilities are handled by the game engine is prone to being confusing. Perhaps ability copies should be disambiguated with numbering. Also it would be useful to have the targets that might carry over listed on the prompt as a measure of convenience.