The analysis engine will query the value for WT.vr.rac only on the first hit of a visit, or when the value is changed from a hit with WT.mc_id. Additional hits by the same user will not have the WT.vr.rac parameter added to them by the analysis.
This means that if filtering for a specific Most Recent Campaign ID, a Hit filter will result in only the first hit of the visit being included in the report. A hit with WT.mc_id in it would also be included. When using a Visit filter to include a specific value of the WT.vr.rac, keep in mind the entire visit will be included. This will also include new WT.mc_id values that the user changes to within the same visit. Future visits associated with the excluded Campaign ID would not appear in the report.