We investigate non-local eigenvalue problems governed by the fractional \(\psi \) -Laplacian operator. The main results include the identification of two positive constants, \(\gamma _0 \le \gamma _1\) , where \(\gamma _1\) is shown to be an eigenvalue, and any \(\gamma \le \gamma _0\) is proven not to be an eigenvalue. Furthermore, assuming the N-function \(\Phi \) satisfies the \(\Delta _2\) -condition, we prove that \(\gamma _1\) is isolated on the right. This isolation result is a key tool in deriving subsequent Hölder regularity estimates. All findings are developed in the setting of non-reflexive spaces, characterized by the failure of the \(\Delta _2\) -condition for the complementary N-function \(\overline{\Phi }\) .