I ran into this exact same issue and Lorex support provided me with a newer firmware, 00053. This has fixed the RTSP stream issue and since they sent me a mediafire link that I'm not sure will stay available, I'm attaching the firmware here.
Thanks all. Turning night mode on and off a few times did not change anything. I logged into the NVR from Internet Explorer (only thing it supports) and found a hidden setting I never noticed before under 'Scene Mode' that allows me to adjust the red and blue gain. They were both set at default...
I installed a Lorex IP 1080p camera system a few years ago and never got around to putting up the cameras at the side and rear of the house until now.
One of the cameras seems to have a purple tint to the image so I thought the IR filter was stuck and swapped it out with a different camera but...