Can you feel or tell if any of them have water coming from them? They may very well need repaired if they are not popping up. In some pools, they are your only returns. That's the way mine is, unless I have the valve on for the loveseat returns, or the valve for the aerator turned on. In mine, only 2 are active at any one time, and only for probably less than a minute, then it goes to the next set. If you have no other returns that you know water is coming back into the pool from the filter, then you need to have them repaired.
Are you sure your filter isn't in backwash mode or waste mode? Are you losing any water when your pump is running?
Some of the actuators for infloor systems have a little screen that needs to be cleaned, periodically. If your filter is operating properly, it really shouldn't be clogged up much, ever. But, if your filter has a problem, the little screen could be totally clogged up. Also, if your system is anything like mine, with the loveseat or aerator, or if you have other returns, I suppose it could be possible that the valves for those systems may be turned on enough, that there is not enough pressure to also pop up the returns in the floor.
Also, make sure there isn't a valve that may be preventing the water from flowing to/through the actuator.
Plumbing can vary from one pool to the next with these types of things. If you could take a pic of your mechanicals (pump, filter and all the plumbing), perhaps we could make a better SWAG at it.