For every \(0<r<\frac{1}{2}\) , we will construct a flat Kähler manifold M and a relatively compact domain with smooth boundary \(\Omega \subset M\) that is Stein but not hyperconvex such that the Bergman projection P on \(\Omega \) is regular in the \(L^2\) Sobolev space \(W^s(\Omega )\) for all \(0\le s<r\) but irregular in \(W^r(\Omega )\) . On these domains, we will also construct \(f\in C^\infty ({\overline{\Omega }})\) such that \(Pf\notin C^\infty ({\overline{\Omega }})\) . We will prove the same result for the invariant Bergman projection on (2, 0)-forms. These domains are modeled on a construction of Diederich and Ohsawa.