Just an update: after 40+ hours of testing, process tracing, server changes, etc. I have determined the fault lies squarely with phpthumbof (not phpthumb). I am not using Gallery or any add-ons like that. When I have phpthumbof installed, I have the problem (even though I have 0 phpthumb calls on the site). When phpthumbof is uninstalled, problem goes away. A good example is having an image based TV that when accessed, causes phpthumbof to spawn of crazy processes on the server even though phpthumbof has nothing to do with my TV nor is phpthumbof used anywhere on the site - just simply installed in the package manager. That's it. Crazy.
My solution was simple: just don't use it. I completely uninstalled phpthumbof and everything runs great. I'm fortunate in this case that it's on a site where the client is extremely Photoshop savvy and can crop images to the exact dimensions I need for each TV use. I realize this isn't the case for most sites.
The blank HTML thing in the Manager I have run into in the past a long time ago. I can't recall what the issue was. It's just another one of those things that makes me hate ModX. Revo is awesome in so many ways and I love it dearly, but wow, is it ever filled with a lot of weird quirky issues that lurk around every corner. I lose sleep at night thinking about the mission critical sites I have running on ModX knowing that the boogie man can pop out any time and ruin my life (and it has on many occasions). However, that's a separate rant
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