GB parental ratings not available to manually select

[chenks]

If you have an unrestricted user, all available parental ratings will be shown in the filter.  Including from other regions.

yes the user is unrestricted, but the only parental ratings i can select from are shown in the screenshot.
selecting 15, and not GB-15, means that when applying a filter i have 2 separate 15 ratings, 15 and GB-15. none of the GB prefix ratings are on the list to select.

Do some of the shows in your library that don't have UK ratings from your primary metadata provider?

i don't know what you mean by that.
the issue applies to any of the content, be it movies or tv shows.

for movies, which is the library that is affected the most, the primary metadata fetcher is TheMovieDB, then The Open Movie Database