lsp-grammarly-dialect has no effect

I tried to get British suggestions, but despite setting lsp-grammarly-dialect to "british", the sentence Blue is my favourite colour. gets corrected twice (favourite -> favorite, colour -> color). In other words, American spelling is used despite the setting.
I'm including the *lsp-log*.
Command "marksman" is not present on the path.
Command "marksman" is not present on the path.
Command "marksman" is not present on the path.
Command "marksman" is not present on the path.
Command "texlab" is not present on the path.
Command "digestif" is present on the path.
Command "texlab" is not present on the path.
Command "digestif" is present on the path.
Found the following clients for /tmp/emacs-home/src/foobar.tex: (server-id digestif, priority -1)
The following clients were selected based on priority: (server-id digestif, priority -1)
Command "marksman" is not present on the path.
Command "marksman" is not present on the path.
Command "marksman" is not present on the path.
Command "/tmp/emacs-home/.emacs.d/.cache/lsp/npm/@emacs-grammarly/grammarly-languageserver/bin/grammarly-languageserver --stdio" is present on the path.
Command "marksman" is not present on the path.
Command "/tmp/emacs-home/.emacs.d/.cache/lsp/npm/@emacs-grammarly/grammarly-languageserver/bin/grammarly-languageserver --stdio" is present on the path.
Found the following clients for /tmp/emacs-home/src/foo.md: (server-id grammarly-ls, priority -1)
The following clients were selected based on priority: (server-id grammarly-ls, priority -1)
Ready!
Initializing...
Initialized!
open file:///tmp/emacs-home/src/foo.md
Command "texlab" is not present on the path.
Command "digestif" is present on the path.
Command "/tmp/emacs-home/.emacs.d/.cache/lsp/npm/@emacs-grammarly/grammarly-languageserver/bin/grammarly-languageserver --stdio" is present on the path.
Command "texlab" is not present on the path.
Command "digestif" is present on the path.
Command "/tmp/emacs-home/.emacs.d/.cache/lsp/npm/@emacs-grammarly/grammarly-languageserver/bin/grammarly-languageserver --stdio" is present on the path.
Found the following clients for /tmp/emacs-home/src/foobar.tex: (server-id digestif, priority -1), (server-id grammarly-ls, priority -1)
The following clients were selected based on priority: (server-id digestif, priority -1), (server-id grammarly-ls, priority -1)
Ready!
Initializing...
Initialized!
open file:///tmp/emacs-home/src/foobar.tex
create text checking session for "file:///tmp/emacs-home/src/foobar.tex" with {
  "documentDialect": "british",
  "documentDomain": "general",
  "suggestionCategories": {
    "fluency": "on",
    "missingSpaces": "on",
    "nounStrings": "on",
    "numbersBeginningSentences": "on",
    "numbersZeroThroughTen": "on",
    "oxfordComma": "on",
    "personFirstLanguage": "on",
    "possiblyBiasedLanguageAgeRelated": "on",
    "possiblyBiasedLanguageDisabilityRelated": "on",
    "possiblyBiasedLanguageFamilyRelated": "on",
    "possiblyBiasedLanguageGenderRelated": "on",
    "possiblyBiasedLanguageHumanRights": "on",
    "possiblyBiasedLanguageHumanRightsRelated": "on",
    "possiblyBiasedLanguageLgbtqiaRelated": "on",
    "possiblyBiasedLanguageRaceEthnicityRelated": "on",
    "possiblyPoliticallyIncorrectLanguage": "on",
    "punctuationWithQuotation": "on",
    "readabilityFillerwords": "on",
    "readabilityTransforms": "on",
    "sentenceVariety": "on",
    "spacesSurroundingSlash": "on",
    "splitInfinitive": "on",
    "variety": "on",
    "vocabulary": "on"
  }
} 
text checking session for "file:///tmp/emacs-home/src/foobar.tex" is ready
ready file:///tmp/emacs-home/src/foobar.tex
connecting file:///tmp/emacs-home/src/foobar.tex
checking file:///tmp/emacs-home/src/foobar.tex
idle file:///tmp/emacs-home/src/foobar.tex
{
  "range": {
    "start": 43,
    "end": 55
  },
  "content": "{\"ops\":[{\"insert\":\"Hello\",\"attributes\":{\"type\":\"important\"}},{\"insert\":\",\",\"attributes\":{\"type\":\"main\"}},{\"insert\":\" world!\"}]}"
}
checking file:///tmp/emacs-home/src/foobar.tex
idle file:///tmp/emacs-home/src/foobar.tex
{
  "range": {
    "start": 58,
    "end": 70
  },
  "content": "{\"ops\":[{\"insert\":\"Hello \"},{\"insert\":\"world\",\"attributes\":{\"type\":\"main\"}},{\"insert\":\"!\"}]}"
}
checking file:///tmp/emacs-home/src/foobar.tex
idle file:///tmp/emacs-home/src/foobar.tex
checking file:///tmp/emacs-home/src/foobar.tex
idle file:///tmp/emacs-home/src/foobar.tex
emacs-grammarly / lsp-grammarly

lsp-grammarly-dialect has no effect #57
