Can't get the Two By Two achievement in survival

Do you have the 1.20 data pack enabled or is this also the case without the 1.20 data pack?

I believe they are talking about a feature that has not been added yet: the ability to find sniffers or eggs naturally.

They're talking about the "breed all mobs" advancement requiring the sniffer, despite it being spawn egg only right now.

The question is, is that also the case without the 1.20 data pack enabled.

Oh, I didn't know you shouldn't be able to get it with datapacks enabled, sorry

WAI per fixing of MC-260098.

Yes, as long as this issue only happens with the experimental data pack, this is not a real issue. After all features included in that pack are still under development and not fully implemented.