Hello...
(ASUS model Q524UQ, Win10 Ver 1709 64-bit, 12GB ram,i7-7500U @ 2.70 GHz, 2TB HD, Focusrite Scarlett Solo, Sonar Platinum.)
 
I have a project with 17 midi tracks and 7 tempo changes for about a 4.5 minute piece.  There are no effects at all.  I use it to generate audio files and then i remove the audio files after exporting them.  I shift from tempos 76, 122, 91, 76, 91, 122, 91.  I was able to generate all the audio files I needed without any issues.
 
Now I have to go back and recreate the bass audio tracks.  But when I play the project it now plays back at a slower tempo than originally even though the Tempo view shows the same settings as before.  I can hear the tempo changes kick in but they all play back slower than before.  Why would this happen?  The main thing I've had to do to switch back and forth between the midi and audio projects is to adjust the laptop's sound playback/recording settings and the edit preferences within Splat.
 
This happened to me once before.  At that time, I determined how I would have to reset the tempos to get them to play at the right pace.  After I did that, i was fine until the next day when i reopened to the project and played it - then the adjusted tempos no longer corrected the slow down but they all played at the faster tempos!  So i reset it all back again to the origin tempos and then it played correctly again.  Now its been about 6 weeks since then and now the project is back to playing at the slower pace again.  It seems crazy to have to change the tempos again to get it right only to have the project playback too fast later on.
 
What in the world is going on with it?  Does anyone have any thoughts on what could cause this?
 
Thanks for any help.
Alan

Your Sample rate is obviously changing each time you open the project. 

Thanks for that pointer.  I'll dig into the sampling parameters and see what I may have to do.
 
BTW, to get around it for now, I created a new project and copied my tracks to it and repeated the tempo changes.  Luckily there are no effects so it wasn't too time consuming.  In the new project the song now plays correctly.  But I know this affliction could strike there at any time so i'll see about the sampling parms.
 
Thanks, 
Alan

Would an incorrect sample rate affect an all-MIDI project? I don't actually know the answer to that question, but my first intuition is no, it would not.
 
Here's a last-ditch workaround that might do the trick: delete everything from the project except that bass MIDI track and save the project under a new name. 
 

bitflipper
Would an incorrect sample rate affect an all-MIDI project?

Probably not. The only thing changing the sample rate of an all-MIDI project might do is cause a plug-in failure if a plug-in cannot handle the new sample rate. Cakewalk DAWs do not fix the sample rate of a project until the first audio clip is recorded. Once recorded the the sample rate of a project is determined by reading the file header of the first audio file. Project sample rate problems occur when the sample rate in the file header is wrong. This happens when the interface is sending data at a sample rate different from the setting in SONAR. If there is no audio in the project, the sample rate may be changed at any time.

scook
Cakewalk DAWs do not fix the sample rate of a project until the first audio clip is recorded.

Well, to be semantically picky...technically SONAR does have to at least pick an initial sample rate for the project, else you wouldn't be able to mix virtual instruments with different sample rates. But yes, there is no penalty for changing it.
 
Thanks for confirming my guess that sample rate has no bearing on tempo.
 

bitflipper

scook
Cakewalk DAWs do not fix the sample rate of a project until the first audio clip is recorded.

Well, to be semantically picky...technically SONAR does have to at least pick an initial sample rate for the project
 

I guess it depends on how one defines "fix." The project sample rate is initialized from the default in preferences or New Project dialog, however; the sample rate is not stored in the project. If an audio clip is not created before the project is saved, the next time the project is opened it will use the default value from preferences. Changing the default value in preferences effectively changes the sample rate for all projects that have no audio data.

Thanks for pointing out the fact about sample rate and midi, I didn't know that one,,, but This threw me off 
 
"There are no effects at all.  I use it to generate audio files and then i remove the audio files after exporting them. 
 
So I assumed this was the common sample rate playback issue not being able to think of what else could cause this.. I myself have not noticed a noticeable tempo difference only the whole step down between 44.1 and 48. 
 

Thanks everyone for your information.  Thanks to your posts I went back into the Edit/Perferences/Audio/Driver Settings to see if there was anything to change that looked like it might help.  I changed the bit depth from 24 to 16, and clicked on the box '64-bit Double Precision Engine'.  Then I ran the Wave Profiler even tho that doesn't seem to have anything to do with midi (I hadn't run that since I setup Splat on my new laptop).  After that the slowed project played back correctly.  This could be just a coincidence.  I'm not saying that fixed it but at least the problem hasn't come back yet. 
 
There are many parms in the Audio Settings & Playback&Recording panels that I do not understand so i'll be trying to learn more about what those settings are for.
 
Thank you
Alan

None of what you did would change anything to solve your issue, the issue might be your using the wrong audo driver. You cannot run the Wave profile in ASIO mode so I would assume you are not using your Focusrite ASIO driver.
Make sure to download and install the latest driver from the Focusrite web site and follow the instructions.
Then in the Preferences set the Audio driver mode to ASIO. 
You should use 24 bit, not 16. And don't check the 64 bit engine, that's an option that needs to be understood before using. I certainly don't use it. 
Clock rate is not bit rate. Clock rate will normally be 44.1 or 48.