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I have observed the provided code snippets, however, as the localization process includes initially loading the required localization resources and I am not sure how and when this is performed on your side, it would be highly appreciated if you could provide me with a small sample demonstrating the overall configuration of your application along with some test data.
Having a sample that I can debug on my side will be extremely helpful in further investigating this matter.
Additionally, in the meantime, a simple workaround approach I could suggest is manually setting the PREV and NEXT buttons labels as desired by using the locale.prevPageLabelText and locale.nextPageLabelText options.
Thank you for your cooperation. Looking forward to your reply.
Sincerely, Riva Ivanova Associate Software Developer