I have to also have the view that even if the only thing that changed was Sonar, that there may be one or more issues in plugins that are only exposed by the Sonar code, but not CAUSED by the Sonar changes.
This is quite common in things like plugins, as every developer has to interpret the specifications for things like VST 3, and often these kinds of specs can be interpreted in multiple ways, if some parts of the specifications are a bit on the vague side. So, it is quite possible that Sonar is correctly following these specifications, but some plugin is not quite doing the same kind of thing in THEIR interpretation of the specification, then problems can show up after updating Sonar - when the fault may actually lie within the plugin code, and only just now failing.
I LITERALLY had this happen with a program I use, called Forte, from a company called Brainspawn. (GREAT program for live gigging for keyboard players, by the way), and my Presonus AudioBox 1818 VSL audio interface. In this case, Forte got updated, and problems immediately showed up with it following the update, but it turned out that the Presonus developers had used some really obscure parameter in their drivers that only got exposed through the Forte update - but the problem was actually in the Presonus use of the obscure parameter. The Brainspawn folks actually entered into dialog with me, and they were kind enough to actually change their product to allow the Presonus use of this goofy parameter that nobody else on the planet was using, so that's how my situation got resolved. The point is that these kinds of scenarios actually DO exist.
Bob Bone