Hi @shce !
What are those three zero components at the end of x?
As @cvanaret guessed, Percival.jl is actually adding slack variables to your inequality constraints before solving, which explains why the dimension is augmented.
Why is the last component of the initial condition not present in the vector?
Well spotted, that was a bug, I think if you update your packages now, this should be fixed.
Moreover, when I try to specifically set the initial guess with the x=x0 keyword argument
Again well spotted, Percival was expecting a vector of the new size (with slack variables there). I will try to fix this for the next release (the main branch should work though).