Here's what makes this block a problem block:
a larger than 1/4" seam
and seams that are not pressed consistently.
Unfortunately, attempting to match the seams created a pucker due to the large and inconsistent seam allowance.
Now, how to get a consistent 1/4" seam.
First, cut two 2 1/2" strips for testing. If your machine has a foot with a 1/4" guide, use it. Otherwise, use a stack of post-its, sticky back foam, or some other fabric guide that can be set 1/4" away from the needle.
|Foot with a 1/4" guide|
|Post-its to act as a seam guide|
With the two fabric strips, sew a 2" long scant 1/4" seam.
Press the seam to set it, then press the seam to one side, preferably the dark side. Place a square ruler on top, measure from the edge to the seam, then from the seam to the other edge.
With the scant 1/4" seam, my test piece measures 2 1/4",
2 1/4", and 4 1/2" overall, like it should. If yours does not, keep adjusting your needle placement or your guide placement until you get that scant 1/4" seam.
Now for pressing. Press, do not iron! Pressing means going up and down with the iron, not side to side. And always press the seams to the darker side, and be consistent. That way, when joining blocks, the seams will nest, creating perfect matches.
Try these techniques and I'm positive you'll see an improvement in your piecing, and an elimination of a lot of frustration.