If you're using ArcGIS Pro to reproject data between the GDA94 and AGD84 datums, for example using the "Project" geoprocessing tool, the default transform method is NTv2, but this is not valid for some states of Australia. This can lead to results which are out by hundreds of metres. So, if you're converting data from/to AGD84 that is located in the NSW, Victoria, Tasmania, or the NT, you should select a different transform method, such as one that uses a 7 parameter similarity transform.

Please see appendix B of the GDA Technical Manual for a map showing the coverage of the AGD84 NTv2 file.