Hi
How many Rapture Session instrument tracks can I have in a project.  I've used it on various occasions to create two or three tracks in a rough project and have regular problems such as not being able to open the instrument in one of the tracks and having to reload it, no sound and even one Rapture Session recorded sound changing pitch when I add another track of any type.  I wonder if I'm using it correctly.

Assuming you are still using SONAR Artist, there is no instrument limit imposed by the software. The problem seems similar to your previous post http://forum.cakewalk.com/FindPost/3608194
 
It might be time to provide some details about the rest of the software and hardware in use.
 

Hi Thanks. 
I'm using
Sonar Artist (latest update)
On this occasion I was using a Steinberg UR22mkII interface and a Roland A300 Pro controller.  I sometimes use a Boss GT-001 interface for guitar parts.  I use an Akai LPK 25 key controller now and then.
I have an intel core i5 processor 1.6 GHz 2.30 GHz and 8GB Ram and have Window 10 home version 1703
I don't have a permanent set up. (Kitchen table recording) I sometimes listen back to recordings in between sessions using just the laptop and internal sound card.  So I'm changing drivers at times. 

Continually changing setups may be the source of some of your problems. Maybe simplify the setup to one interface and one controller for while.  For example, while the GT-001 can directly connect to the PC, it can also work through the UR22. Yeah, it is having to convert the signal from digital to analog and back but that should not make that big a difference.
 
Artist places no limit on the number of instruments in a project. That said, there are limits imposed by hardware. Constantly messing with you setup makes it hard troubleshoot and tune the PC for best performance. In addition, programs in Rapture Session vary quite a bit in the load they place on the hardware.
 
No sound could be a couple of things such as trying to play notes out of range for the particular program or unexpected MIDI data. All the Cakewalk sfz engine synths shut down when they encounter unexpected data. This is often caused by using 3rd party MIDI clips. It can be fixed by removing the offending data from the clips or enabling "Do not intercept NRPNs" in the VST Plug-in Properties found in the VST2/3 drop down above the Rapture Session UI.
 
Having a track unexpectedly change pitch could be a MIDI routing problem and a failing controller pitch wheel.
 

Thanks for the info. Yes I think i should try having a consistent set up and see how things go.