Audio problems with sends and looping

I'm having intermittent problems with sends & effects when looping sections of a project. It's really weird. Here's an example: I have 8 bars of a synth part looping. It's sent to a bus that has console emulation on it (the bus variety). Every now and then (it doesn't happen all the time), Sonar will play one iteration of the loop normally, and then from the second loop onwards the sound is severely out of phase. If I turn off console emulation, sometimes it goes back to normal, other times it doesn't. Sometimes I have to stop playback and start again and other times I have to close the project and open it again for the out of phase sound to go away. If I turn the bus's ProChannel off, the problem doesn't happen. I have nothing else in the ProChannel at this point. Sometimes it just doesn't happen for ages.      
 
It also happened with the Valhalla Room plugin once, and it bugged me for ages and then fixed itself. 
 
Another weird thing which I don't understand is that if I insert the ProChannel tube saturation on a bus and turn on the "II" mode, it seems to obliterate the highs and I get a very deadened sound, not like using it on a normal track at all. The "I" mode sounds fine. Does anyone else get the same?