Infopath / SP – Append Changes field only shows last 4 updates

I am really stuck with this one! I have a multi line field which I have set to append changes. At various stages of the form I use this field to capture a specific detail (button push sets field value). So as I am working my way through the process each item is captured exactly as it should be. There is 9 details in all. But as I work my way through the repeating table only shows the last 4 updates made.
I have looked at every setting that I can think of and cannot find where this is going wrong. I have done this with another form with no issues at all. Any ideas or help would be greatly appreciated!

D