Some people on my team cannot tag their colleagues in tickets. When I type in the "@" and type a name, the name turns blue and the that person if notified about the mention. A group of people on my team cannot mention people -the name stays as regular text. I have included an image of what it looks like for me, but the other team members do not get this blue text.
From my end, it looks like they have the same permissions access as the rest of the team. 
