How can I get mp3tag to read pre-existing "Initial key" tags?

How can I get mp3tag to read and display pre-existing "Initial key" tag info please?

I have been able to add in an "Initial key" column, but it will not display any pre-existing tag info.

I have been able to add a field to the panel on the left, which I can use to enter "Initial key", which is read and displayed in the "Initial key" column on the right.

But please can you tell me how to already existing "Initial key" tag info to show up? Please keep it simple and step by step (I'm off work after an accident and brain does not seem to be working well and I can't wear my spectacles either!) Thank you.

Try INITIALKEY instead of "Initial key".
Here are the tags that are read by MP3TAG and there names in other programs.

Thanks. I will look into that.