Also, verify that the hardware sends on the master are routing to the proper hardware outputs. I had this recently where I fiddled with several audio drivers to test my USB headset's mic and when I went back to the ASIO drivers of my interface Reaper got confused and routed both master hardware sends to the same outputs (actually the irritation was in audio driver preferences, first and last outputs were set the same).
Panning now doesn't dissolve to nothing going Right, but lowers the volume equally going left and right without actually panning. Full volume down the middle.
Thanks so much for the help so far! I've gone to the M Audio site and tried to download a driver but when I select what I have it says: "There are currently no drivers available for this product and operating system." I'm running OSX Yosemite (10.11.6). I have 8GB of RAM. Again, I have no problem with panning if I track with Garageband, or Reaper 64 bit - but if I go with Reaper 64, I don't have my purchased plugins. Thanks again!
WhooHoo! I thought I had checked before but must not have, or at least not correctly. There seems to have been some hidden FX on the master. I removed them and now I can pan! Thanks so much VinodXagent and others for your help! Cheers!
--------------------- I used to have a picture of an E30 here.