Netherwalk question

I was running arenas today and had a healer complaining he couldn’t heal me during netherwalk. I have never heard this before from any other healer and haven’t noticed myself during play. Is this something I missed or was it a bug / he doesn’t know what he’s doing lol. My first thought was los, but they kept saying they couldn’t heal me

Well it does make you immune. I wonder if its coding is like detainment talented imprison?

I main a holy priest and I can not heal while a DH in nether walking, it makes you unselectable as if you were lining