Manually adding firearm proficiency through the "Proficiencies & Languages" -> "Add New Proficiencies" -> "Weapon" -> "Firearm" does not add the proficiency bonus to firearms for my character sheet. I instead have to manually add specific firearm proficiencies. I did notice that when adding the "Gunner" feat, the proficiency for firearms is listed as "Firearms" with the s at the end and everything works, while the manually added proficiency is "Firearm" without an s at the end of the word. I'm not sure if that is part of the issue or not, but I thought I'd mention it just in case.
Manually adding firearm proficiency through the "Proficiencies & Languages" -> "Add New Proficiencies" -> "Weapon" -> "Firearm" does not add the proficiency bonus to firearms for my character sheet. I instead have to manually add specific firearm proficiencies. I did notice that when adding the "Gunner" feat, the proficiency for firearms is listed as "Firearms" with the s at the end and everything works, while the manually added proficiency is "Firearm" without an s at the end of the word. I'm not sure if that is part of the issue or not, but I thought I'd mention it just in case.