diff --git a/Code/Form1.cs b/Code/Form1.cs
index fbb0ead..e0b6738 100644
--- a/Code/Form1.cs
+++ b/Code/Form1.cs
@@ -611,6 +611,7 @@ namespace Flowframes
 
         private async void runStepBtn_Click(object sender, EventArgs e)
         {
+            ValidateFactor();
             SetTab("interpolate");
             await InterpolateSteps.Run(stepSelector.Text);
         }
diff --git a/Code/IO/Config.cs b/Code/IO/Config.cs
index 502f76d..a982f33 100644
--- a/Code/IO/Config.cs
+++ b/Code/IO/Config.cs
@@ -279,7 +279,7 @@ namespace Flowframes.IO
             // Debug / Other / Experimental
             if (key == Key.ffEncPreset)   return WriteDefault(key, "medium");
             if (key == Key.sbsRunPreviousStepIfNeeded) return WriteDefault(key, "true");
-
+            if (key == Key.allowCustomInterpFactor)     return WriteDefault(key, "True");
             if (type == Type.Int || type == Type.Float) return WriteDefault(key, "0");     // Write default int/float (0)
             if (type == Type.Bool)                      return WriteDefault(key, "False");     // Write default bool (False)
             return WriteDefault(key, "");