How do I override a single string in _data/ui-text.yml

[GregWoods]

I have searched through the docs, and I have found references to setting strings in _data/ui-text.yml, but I can't get it working.
I am using a remote theme, with a some small changes to _layout\archive and _includes\archive-single.html.
I like the way I can copy over a single file in the theme and make my changes, and it will prefer my file over the remote one. But the same logic doesn't seem to work with ui-text.yml
I have tried modifying just one string, and I've tried copying the entire file and making my alteration. Neither is working for me.

Any help appreciated

Jekyll 3.8.5
minimal-mistakes 4.19.0

[mmistakes]

Same logic works for _data files too. Any text you override in that file will be used by the theme.
Can you provide a link to a public repo? Common issues is if you edited that YAML file and it's not valid anymore (incorrect indents or a bad string).

Also did you make your text edits under the correct locale that corresponds to what you have set in _config.yml

[GregWoods]

I had multiple issues.

• An indenting error after the copy/paste
• I had assigned to the default en locale instead of en-GB, which would have been Ok, had I left in the :

en-GB:
  <<: *DEFAULT_EN

at the end.

Thanks pointing out the obvious gotchas. It was a great help just knowing I was on the right lines!