Hi I'm currently doing some work on Zipper Grids (on ArcGIS Pro 2.5) and have come across an error with the UTM Grid Zone Designator.
It is giving me a UTM Designator of 54I & 55I. This UTM zone does not exist. The UTM zone my area of interest falls within is 54H. This is picked up in the meter reference guide just not the grid.

Any help you can provide would be greatly appreciated.
I'm not sure if it's my ignorance, I have done something wrong or if its a bug (I'm assuming its the former).
Thanks,
Rowan