_position inside [if] doesn’t work

Hello,
I’m using the pod template system and I need a conditional that is only executed on the 8th loop. I’ve been trying to use _position inside an [if] but it doesn’t work. But if I print it as a variable it works:

[if field="_position" value="8"]<p>Test</p>[/if] <-- This doesn't work
{@_position} <-- This works. Prints 1, 2, 3... on each loop.

I’m calling the template using a pod shortcode like this: [pods name=”themes” template=”tgs-home-artisticspot”]
If have tried it in version 2.8.10 and the lastest 2.8.17.

Thank you very much.

Gerard.