SONAR Platinum (32-bit) on Windows 64
ECHO Layla 3G Audio interface.
I use 44.1/24-bit depth for audio recording.
In SONAR X3 Producer:

 
In SONAR Platinum 2015.1:

 
I'm guessing this is a visual display bug, and that my recorded audio is in fact 24-bit...

Is this a new project or is there recorded auto in it? 

For a new project the Control Panel refers to the "Record Bit Depth" in Preferences > File > Audio Data not the "Audio Driver Bit Depth" in Preferences > Audio > Driver Settings. Otherwise it shows the bit depth of the audio files in the open project.  Either way the value is not related to the "Audio Driver Bit Depth" in Preferences > Audio > Driver Settings.

Huh. Interesting, scook, I didn't realise.
This is an existing project with existing audio, but the real issue is, as you point out - that the File Record Bit Depth did not get correctly migrated from X3 Producer to SONAR Platinum.
 
My mistake. This is not an issue. I've updated my problem report to ask them to close it as User Error.

OK, I will move this out of Problem Reports into SONAR forum.