Why doesn't day 21 work?

The example works. I've stepped through like 20 operations manually.
What the hell?

1 files changed, 100 insertions, 0 deletions

diff --git a/input/day21.txt b/input/day21.txt
new file mode 100644
index 0000000..68bb697
--- /dev/null
+++ b/input/day21.txt
@@ -0,0 +1,100 @@
+swap position 5 with position 6
+reverse positions 1 through 6
+rotate right 7 steps
+rotate based on position of letter c
+rotate right 7 steps
+reverse positions 0 through 4
+swap letter f with letter h
+reverse positions 1 through 2
+move position 1 to position 0
+rotate based on position of letter f
+move position 6 to position 3
+reverse positions 3 through 6
+rotate based on position of letter c
+rotate based on position of letter b
+move position 2 to position 4
+swap letter b with letter d
+move position 1 to position 6
+move position 7 to position 1
+swap letter f with letter c
+move position 2 to position 3
+swap position 1 with position 7
+reverse positions 3 through 5
+swap position 1 with position 4
+move position 4 to position 7
+rotate right 4 steps
+reverse positions 3 through 6
+move position 0 to position 6
+swap position 3 with position 5
+swap letter e with letter h
+rotate based on position of letter c
+swap position 4 with position 7
+reverse positions 0 through 5
+rotate right 5 steps
+rotate left 0 steps
+rotate based on position of letter f
+swap letter e with letter b
+rotate right 2 steps
+rotate based on position of letter c
+swap letter a with letter e
+rotate left 4 steps
+rotate left 0 steps
+move position 6 to position 7
+rotate right 2 steps
+rotate left 6 steps
+rotate based on position of letter d
+swap letter a with letter b
+move position 5 to position 4
+reverse positions 0 through 7
+rotate left 3 steps
+rotate based on position of letter e
+rotate based on position of letter h
+swap position 4 with position 6
+reverse positions 4 through 5
+reverse positions 5 through 7
+rotate left 3 steps
+move position 7 to position 2
+move position 3 to position 4
+swap letter b with letter d
+reverse positions 3 through 4
+swap letter e with letter a
+rotate left 4 steps
+swap position 3 with position 4
+swap position 7 with position 5
+rotate right 1 step
+rotate based on position of letter g
+reverse positions 0 through 3
+swap letter g with letter b
+rotate based on position of letter b
+swap letter a with letter c
+swap position 0 with position 2
+reverse positions 1 through 3
+rotate left 7 steps
+swap letter f with letter a
+move position 5 to position 0
+reverse positions 1 through 5
+rotate based on position of letter d
+rotate based on position of letter c
+rotate left 2 steps
+swap letter b with letter a
+swap letter f with letter c
+swap letter h with letter f
+rotate based on position of letter b
+rotate left 3 steps
+swap letter b with letter h
+reverse positions 1 through 7
+rotate based on position of letter h
+swap position 1 with position 5
+rotate left 1 step
+rotate based on position of letter h
+reverse positions 0 through 1
+swap position 5 with position 7
+reverse positions 0 through 2
+reverse positions 1 through 3
+move position 1 to position 4
+reverse positions 1 through 3
+rotate left 1 step
+swap position 4 with position 1
+move position 1 to position 3
+rotate right 2 steps
+move position 0 to position 5
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