modify /ltm virtual-address <x.y.z.w> enabled no|yes not behaving as expected

Hi, folks,

     In preparation for a migration, I'm experimenting with turning off access to iApps via the CLI. The most obvious way I've found of doing this is to disable the virtual address thus: modify /ltm virtual-address <x.y.z.w> enabled no

     When I do that, the virtual address shows unavailable in the GUI and the iApp becomes unavailable in the browser, as expected and, when I issue the same command with enabled yes, the virtual address shows available in the GUI and the iApp becomes available in the browser, again as expected. However, if I toggle the address with enabled no again, the virtual address shows unavailable in the GUI but the iApp remains available in the browser, even if I dump cache.

     Then to really complicate things, even though there's no caching enabled, if I wait three minutes, the iApp finally becomes unavailable. This puzzles me!

     What am I missing? And is there a better way to make iApps unavailable from the CLI?
Thanks,

     John A