Ultimately, this is the brands’ decision about which teams they want to target through Experticity. It's common for brands to change their target audience or only give access to a specific group or team position within a team. This could explain why you had access and no longer do, or why you do not have access when a colleague does. If you qualify for a different team that has access to the brand, you can apply to that team.
To ensure that you are receiving all the access for which your team qualifies, please make sure you have fully completed your profile. Information such as date of birth and US shipping address are necessary to populate to gain access to the brands that are targeting you or that you want access to. Beyond that, adding the places you work and organizations you belong to is the fastest way to strengthen your Expert profile, and posting and tagging photos on the Experticity app also helps showcase the type of Expert you are. All of this helps brands find you and recognize you for your expertise.