Is this a custom module or through DNN functionality?

Do you have a lot of caching going on? 

I'm not really sure - I don't do a lot of that in my sites. I have played with role changes and there are some cache clearing that needs to happen if you are doing custom code. I'm pretty sure the "role" pages (admin side) have it as well - but I don't know about when doing subscriptions, ect. Haven't touched that stuff.

I do something very similar on my site - a user can select which modules they want displayed on the front page (a bit like a web parts catalog). Depending on which modules they chose I am amend their roles.

In order for this to work without logging out I use these commands to add/delete roles:

Add

                            DotNetNuke.Security.Roles.RoleController.AddUserRole(dnnUserInfo, RI, PS, DateAdd(DateInterval.Minute, -10, Date.UtcNow), Date.MaxValue, UserId, False)
                            DotNetNuke.Entities.Users.UserController.UpdateUser(PortalId, dnnUserInfo)
 

Delete

                            Dim RC As New DotNetNuke.Security.Roles.RoleController
                            RC.DeleteUserRole(PortalId, UserId, RI.RoleID)
                            DotNetNuke.Entities.Users.UserController.UpdateUser(PortalId, dnnUserInfo)

I then do a post back to my site using                 Response.Redirect(NavigateURL())
 

Then when redisplaying my roles I use the following:

                'Clear  Cache
                DataCache.ClearUserCache(PortalId, UserId)
                DotNetNuke.Security.PortalSecurity.ClearRoles()

                Dim lstUserRoles As String()
                lstUserRoles = objRoles.GetRolesByUser(UserId, PortalId)
 

This does work!

As a side note I am sure that I have read that dynamic role modifiications is supported in DNN v5.0 - maybe someone from the Core team can confirm this?