I am an undetectable guy too... well, actually around .1n (IC test) and .005-.01p (now detectable with Hannah, but previously undetectable) and the yellow show fine in my Picachu, Wolverine, OG OG Pink Lemonade, Pink Floyd, MattV Hornet and a nice Lopries/Lokani that I have. If somebody wanted to argue that MattV Hornet, Picachu and Pink Floyd were all within 2% of each other or even the same coral, I would not argue back. My wolverine only gets yellow tips and corallines - not branches... not sure what other people's do.
Maybe you need some more daylight? I keep mine under Halides, so intensity nor spectrum are a problem. Do you supplement with any full-spectrum lighting (T5) that will have some good yellow, green and red?