[Support] I can't get Composite video to work on any RasPi 3b, 4, or Zero that I own.

[/RaspberryPi]

Hey there.
I'm frustrated.
I'm trying to hook a couple of Pis up to some old CRTs that I have for various reasons. To do this, I'm trying to use the built in Composite, since using that doesn't introduce the added complexity of an HDMI -> Composite converter.
I've simplified my test down to:
Go to NOOBS splash screen press 4 (NTSC composite) connect composite and I get no usable composite.
I hook up my oscilloscope, and I see a waveform that resembles a composite waveform, but my old TVs show nothing, and my LG 43UM7300 (4K TV) says No Signal on composite.
Is the signal too weak?
Am I an idiot?

submitted by /u/Jceggbert5
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