Hi,
I'm having one problem, please find it here. I've created one activity. The activity is only displayed on mobile devices, however it also appears on desktop devices.
I made an audience called mobile device > is mobile device > true, but it isn't working.
It is difficult to provide an answer without having more details of your activity. The logic of your audience sounds correct and I assume it looks like this:
If your audience is correct and your activity is set to use it, then i would raise a ticket with client care.
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