Command Block Tags not Working for Plugin Commands

When I try to use command block tags (@p, @r, @a, and @e) for plugins commands, it simply doesn't work. Nothing happens. When I use names (Like Bob123) in place of the tags it works. This doesn't apply to vanilla Minecraft commands. I have used the command block override feature to fix those. There are no errors in the console, and no output from the command block. It just simply doesn't work. Examples of commands I have tried are /pay @p (Essentials), /mvtp @p [world] (Multiverse), /spawn @p (Essentials, and /eco give @p (Vault).