What's the base rate set to in the simulator?
Regardless, this is probably the wrong hammer for this job.
I wouldn't recommend driving any "production" logic off a simulator tag.
From the tag name, it sounds like you're looking for a "flasher". In Perspective, you really shouldn't use a tag-based flashing approach. Instead, use a style class:
Or if you insist on using a tag, so that flashing is globally synchronized, just use an expression tag with something like:
getSeconds(now(__someRateIntegerInMilliseconds__)) % 2 = 0
If the expression tag is set to 'Event Driven' mode, it'll run as fast as the refresh rate you set on now().