Problems with Access Levels in Membership Plugin.

Hi,
I am trying to achieve the following with the membership plugin, but cannot figure out how to do it.
I am running monthly workshops for selected participants and want the participants of a workshop to access a certain portion of my site. Lets say, if you attend in Jan and March I want you to see the Jan and March categories but not the Feb category.
Another user may have just attended in Feb and thus should only see that category.
I have created access levels for all these months and I was trying to assign multiple categories to a user.
The access levels have a positive access rule set for category = Jan for example. This works fine as long as I only assign one membership level to a user. Once I assign a second membership level to the same user lets say jan and feb, these assignments seem to become mutually exclusive and the user cannot see any protected content anymore. Not sure if I am doing anything wrong or if this kind of setup is simply not supported by this plugin.