Citation Style cannot change
Good morning of afternoon,
I am currently writing a report, and I have a problem with the Citation Style. I used a specific citation style on a precedent report, but it seems that I cannot use this one anymore. When I search for it, it appears grey, and I cannot click on it. I have been trying with other styles, as a test, and the result is the same. If I change my citation style and want to go back to the precedent one, it appears grey and I cannot click on it, and therefore, use it. This is really frustrating, and I have been trying several methods, but none of them worked. I would really appreciate some help, does anyone knows how I could unlock this? You will find attached a screenshot to better understand the situation.