diff --git a/pymoo/core/problem.py b/pymoo/core/problem.py
index 959d887fe..776b5089d 100644
--- a/pymoo/core/problem.py
+++ b/pymoo/core/problem.py
@@ -214,7 +214,7 @@ def evaluate(self,
             try:
                 out[k] = v.astype(np.float64)
             except:
-                pass
+                out[k] = v
 
         if self.callback is not None:
             self.callback(X, out)