If you have room, put your bucket over the post so that the post is now behind the bucket. Place the bucket flat on the ground. Route your chain over the top of the bucket and down to the bottom of the post, wrapping it good around the post so it won't slip. Now, rotate your bucket toward dump while lifting up on the FEL at the same time. The back side of the bucket is nearly even with your lift pins, so you'll have maximum lift plus rolling the bucket down will assist the lift arms. I don't suggest pulling the post all the way out with this method, but just get it lift a foot or so and then remove the bucket and lift from the front as you originally were. If you can't get it from behind the bucket, then you'll probably have to use the 3PH where you have more lift than the FEL.
Nobody can say your TC45DA is or is not working properly because a post can be really tough to pull. However, out at the bucket cutting edge, you don't have nearly the lift that you can create if you are in line with the lift arm pins or even behind them a bit. You should have plenty of room between your torque tube on the loader arms and the back of the bucket or QA plate adapter.