Keeping in mind the first XYZ is worldspace, the other 2 are localspace!
Are the projects literally copied or did you merge parts?.
your control rotation basically determines the projectiles rotation wich isnt good it can cause it to fire in a different direction than you expect
Velocity tab is the direction your projectile goes in when spawned with the Initalspeed variable, thats what i meant with initial direction 
Keep in mind this is the LOCAL space of the projectile so the X Direction it was spawned with is the direction it will fly in.
the constraint works as follows:
constraint Normal = thats the axis it can move in
constraint origin = say for some reason it is spawned at y = 100, if you have snap to plane at start checked it will automatically move it to y = 0 or whatever you have in constrain origin for that axis.
I believe these are WORLD space (someone correct me if im wrong i didnt do all that much with 2D Projectiles)
So you need to be aware of all your Directions for each blueprint and make sure your projectiles X axis (default movement direction) is aligned with wherever you want it to go.
