The behavior you’re seeing is not a bug but rather a known limitation of the series‐solution implementation in Sympy’s dsolve. In the current implementation, when you use the series hint (for example, '2nd_power_series_ordinary'), dsolve returns a truncated power series in terms of arbitrary constants (like C1 and C2) without automatically solving for them using the provided initial conditions.

There isn’t a built-in workaround in the current version of Sympy’s dsolve to automatically eliminate the constants when using the series hint. You’ll need to either post-process the solution or use a different method if you require the IC to be applied directly.