Are you using Add Child or Add Child to Uniform Grid? One returns a generic panel slot hence no row / column ints, while the other returns the pertinent slot type.
Can’t tell for sure but it’s possible the *Add Child to Uniform Grid *is only available in the more recent engine versions. In this case it was added rather than removed.
edit: you can always cast to the correct slot type and then set row / column if your engine version is not exposing this node.