Yeah, it is screen tracing, but why? 
As far as i understand it, screenspace stuff or screen trace is the last resort, the fallback or failsafe method, if everything else fails.
But why does everything else fail at those ramps, so that it has to use screen trace? The only difference between such a ramp and all the other blocks is it´s angle, same for the rect light and it´s emissive block.
Might be worth investigating.