Hi there. New to the forums, and I thought I would give y'all a heads-up about an issue I've been having with KCT. Caveat: I haven't tested this extensively, and I don't have any tasty logs for you (though I could use some guidance on which ones to include in the future, and where to find them). But what I do have is a solution, in case anyone runs into the same issue.
I'm running a fairly huge (for me) modpack, so naturally I get crashes from time to time. But occasionally, I find that KCT stops working when I restart the game after a hard-lock crash. The icon just doesn't show up in the toolbar. I found that it works in new saves, though, so I checked the KCT_Settings.cfg file in the bad save folder -- lo and behold, it was empty. So I copied over KCT_Settings.cfg from the new save (with the settings I want) to the bad save and voila! It works again.
Despite my lack of rigor in tracking down the cause, I still feel like this information could be of some use to someone.
edit: I'm on KSP 1.11.1.3066 and using KCT 1.4.9 from CKAN. I can at least tell you that much.