Homeguards not Activating

After buying homeguards on Ionian Boots of Lucidity , sometimes after porting back to base, the movement speed buff doesn't activate, or is activated, but then disabled after buying an item like Elixir of Wrath . I was playing Shaco at the time. Ive noticed this 3 times today playing various games, but the most recent incident could be correlated to the Elixir.