This might be because you’ve taken them straight out of the fridge, so they have cooled the sauce and are now struggling to get up to temperature to cook. It can be tricky to poach eggs this way, so just carefully turn the heat up and wait until the egg whites start to turn.  Try and bring your eggs to room temperature before adding them into the sauce, but if not, just keep an eye on them and it will happen! My method of using the grill also helps to finish the eggs off and get them to cook through.