This was attempted on PC.

To reproduce bug:
1. Import the attached deck.
2. Open the deck to edit it.
3. Go to the sideboard.
4. Attempt to swap an Orim's Chant in the best-of-1 sideboard with the Tendrils of Agony in the best-of-3 sideboard so it'll show up if you play best of 1.
5. Click done to save changes.
6. Re-open the deck and go to the sideboard.

Actual Results:
The deck stays the same. The Tendrils of Agony remains in the best of 3 sideboard.

Expected Result:
The Tendrils of Agony should move up to the best of 1 sideboard and the Orim's Chant should be moved to the best of 3 sideboard.