the rim tape was already installed by Giant, it is blue and has like a hatch reinforcing pattern on it. The bike did also come with like this 3M blue tape that is different to the one that is already installed.Have you ridden with it, or just waiting for it to seal first? I always find that they never fully seal until the first 2 or 3 km's of riding (keep it to light XC for this myself). Only caveat to this is if they're leaking because the rim strip isn't up to scratch and it's leaking through spoke holes/around the stem. best solution in that case is to redo the rimstrip. second is to add more sealant and make sure you rock the wheel around and well coat the rim to get the sealant to work there (though it makes a mess, particularly when you end up with sealant in the rim cavity and coming out the spoke holes).
when I was looking at the bead of the tyre, about every 5cm along it has tyre nipples sticking out, should I just snip them off? they might be hindering the sealing process