Problems with FG knot

One of my rods has micro guides so I figured it’s time to learn an FG knot. Watched a few tutorials, went fine, first bass I caught on that rod was 4 lbs and Ive caught a few other since with no issue. I tied the FG onto 2 of my other rods and haven’t had the best luck. One of them broke as I was casting and I lost my leader and my jig. 15 mins later, the knot came loose on a fish and lost that too. I think I’m tying it pretty well but is there anything I might be messing up? Maybe I’m just not pulling hard enough to get the grooves into the leader material? I usually pull on it pretty hard.