I believe this is a genuine bug/oversight. While the script can run fine without this fix, DMux8Way is expecting three bits for the sel input, but the compare file only shows two. This made me a bit confused looking at the file and trying to work out the logic, until I realized what's going on.
Since I've been doing my work in Git, I've made a patch for it:
diff --git a/01/DMux8Way.cmp b/01/DMux8Way.cmp
index b34c563..ebf9304 100644
--- a/01/DMux8Way.cmp
+++ b/01/DMux8Way.cmp
@@ -1,17 +1,17 @@
-| in | sel | a | b | c | d | e | f | g | h |
-| 0 | 00 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
-| 0 | 01 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
-| 0 | 10 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
-| 0 | 11 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
-| 0 | 00 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
-| 0 | 01 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
-| 0 | 10 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
-| 0 | 11 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
-| 1 | 00 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
-| 1 | 01 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
-| 1 | 10 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 |
-| 1 | 11 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 |
-| 1 | 00 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 |
-| 1 | 01 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 |
-| 1 | 10 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 |
-| 1 | 11 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
+| in | sel | a | b | c | d | e | f | g | h |
+| 0 | 000 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 0 | 001 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 0 | 010 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 0 | 011 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 0 | 100 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 0 | 101 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 0 | 110 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 0 | 111 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 1 | 000 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 1 | 001 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 1 | 010 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 |
+| 1 | 011 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 |
+| 1 | 100 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 |
+| 1 | 101 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 |
+| 1 | 110 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 |
+| 1 | 111 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
diff --git a/01/DMux8Way.tst b/01/DMux8Way.tst
index 536146d..91469bf 100644
--- a/01/DMux8Way.tst
+++ b/01/DMux8Way.tst
@@ -6,7 +6,7 @@
load DMux8Way.hdl,
output-file DMux8Way.out,
compare-to DMux8Way.cmp,
-output-list in%B2.1.2 sel%B2.2.2 a%B2.1.2 b%B2.1.2 c%B2.1.2 d%B2.1.2 e%B2.1.2 f%B2.1.2 g%B2.1.2 h%B2.1.2;
+output-list in%B2.1.2 sel%B2.3.2 a%B2.1.2 b%B2.1.2 c%B2.1.2 d%B2.1.2 e%B2.1.2 f%B2.1.2 g%B2.1.2 h%B2.1.2;
set in 0,
set sel %B000,
Locked
