This is a c4d bug, nothing to do with octane, it affects any rectangle area light. C4D area lights have 3 parameters which control their size. The X and Y size on the details tab and the Outer radius control above it. The problem is that these numbers all interact, and when you change the width of the light in a take, it also adjusts the outer radius setting. Because changing the height doesnt record outer radius values, any take where you change only the height, breaks when coming back from another take where you adjusted the width... Its stupid, the outer radius setting has no reason to exist.
Personally I do this for multiple lighting shots in the object manager:
I put all shots inside a hidden null. For each take, I set the shot number null to green so it shows up and enable the camera inside. You can now adjust the camera and lighting with takes turned off, safely knowing that one take wont break the others. It also stops your viewport getting filled with lights and cameras from other takes.
Maxon are aware of the problem... however its been 4 years, so don't hold your breath.