I had an issue with redshift. It appears that config.enableRedshift can get stuck. I've seen this on several characters now.

What I saw on a new char:
config.enableRedshift = false is default, works. I made the following changes with reloads after each:
config.enableRedshift = true works
config.enableRedshift = false works
config.enableRedshift = true fails

I went to WTF->eventhorizon.lua where I saw that redshift->isactive was false after the fail. I exited, changed that to true. When I reloaded the game I saw the EH frame for a moment then it flashed off and redshift then continued to work correctly.