Can't create subclip with default shortcut key

With default Resolve keyboard mapping loaded:
- Open clip in source monitor
- Set in and out point
- Press Option - B
- No subclip is created
- In user preferences dialog assign a different shortcut key to 'Create SubClip' command (for example Option - S)
- Save and close preferences dialog
- Press Option - S
- Subclip is created
DaVinci Resolve Studio 15beta2
MacOS 10.12.6
- Open clip in source monitor
- Set in and out point
- Press Option - B
- No subclip is created
- In user preferences dialog assign a different shortcut key to 'Create SubClip' command (for example Option - S)
- Save and close preferences dialog
- Press Option - S
- Subclip is created
DaVinci Resolve Studio 15beta2
MacOS 10.12.6