The easiest way to create a project at a sample rate other than the default specified in preferences is the New Project dialog. Set the desired sample rate in the New Project dialog and immediate record or copy an audio clip into the new project. By adding audio immediately to the project, the next time the project is opened, SONAR will use the sample rate of the audio. If you do not have confidence that your interface is properly switching to the new sample rate, make sure to verify the sample rate in the interface before recording any audio.
 
I do not have MOTU to test but in my case, I can have multiple projects each set to a different sample rate open at the same time. Switching between the projects switches the interface sample rate and shows the current project sample rate in the transport module. The same is true anytime I open a project that runs a different sample rate than the last one opened as long as the project has audio.
 
While SONAR can work with audio clips at different bit depths ALL the audio in a project must be the same sample rate. Dragging a 44.1k file into a 48k project will cause SONAR to convert the 44.1k file to 48k.
 
If a project has audio files referenced in the the same rate is fixed and will not change. If a project has no audio files referenced in it when opened the project reverts to the default in Preferences. Of course, this can be reset by temporarily changing the default and record or copy a clip at the correct sample rate.

Thanks SCook, it's clear now. Yesterday I did do a record test just like you explained and my MOTU passed it fine. I never have more than on e project open, so I won't have any problems with confusing the interface.
 
I'm glad to hear that importing 44.1 into a 48 project will convert it to 48. That's exactly what I need. I now see how the sample rate is recorded in a project it's not in the CWP, but in the audio folder all files have the same sample rate, which explains my original post problem. I was using the same audio folder that I saved a 44.1 wav file.

"What kind of nightmares are you referring to?"
 
Nightmares with one particular powerful laptop,where the sampling rate does not change automatically or it just crashes the motu driver.
This is not a motu only problem it`s an intel,windows and acer problem.
It has nothing to do with your problem.
By the way the 624 works perfect on 2 other win 10 pcs.
Meanwhile i`m still waiting for an update from  these 4 big names.
 
Peace