Word caption numbering is reverting to incorrect number every time a new caption is added

Hi all,

So I'm writing a document that contains a lot of tables. I am captioning them and the auto-numbering based on H1 numbering is working well.

However, I also have tables in my Appendix, which use a different style for the headings: "Appendix H1".

My tables within the Appendix default to continuing H1 numbering. I am able to manually change the field to use the style ref of Appendix H1 instead, and I have ticked the box to preserve formatting during updates (see below)

But whenever I add a new caption anywhere in the document, all the Appendix captions update and revert to using the H1 numbering.

I've made a separate caption style for the Appendix captions, but I can't find how to permanently change the numbering reference to be Appendix H1.

How do I permanently assign Appendix H1 as the field code?