Do you have the RSL5K project file of the controller you think the tag might belong to? Make sure you SAVE after every Edit!
If you do, within the FTVS Project Tree, RSLinx Enterprise/Communications Setup interface bottom window pane (Offline Tag File) pick the Browse button and point the software to the location of the RSL5K project file.
Then, in the left pane of the RSLinx Enterprise Tag Browser, expand the 2501CHCP001 shortcut folder, right-click the Offline sub-folder and pick Refresh; upon Refreshing the Offline folder, a double-click on the folder should let you access the tag you are looking for.
Remember, after every RSL5K edit, SAVE and then REFRESH the FTVS RSLinx Enterprise Offline folder.