Command for scss compilation using ruby sass is 'sass'. Not to confuse with npm scss which is a (somewhat unsupported) JS port.

elsassph · elsassph · commit c9e1bcc826d8 · 2015-09-01T23:32:34.000+01:00
diff --git a/FlashDevelop/Bin/Debug/Tools/css/scss.bat b/FlashDevelop/Bin/Debug/Tools/css/scss.bat
@@ -1,2 +1,2 @@
-@scss %*
-:: scss <options> in:out
+@sass %*
+:: sass <options> in:out

-Original file line number
+Diff line change
@@ @@ -1,2 +1,2 @@ @@
 -@scss %*
 -:: scss <options> in:out
 +@sass %*
 +:: sass <options> in:out