Hook mushrooms don't seem to propagate at all, despite there being room to do so. They are planted on valid spaces, such as ceiling mushrooms, but do not spread. Setting the random tick speed to an arbitrarily high value such as 1000 or 10000 yields the same result. There is no way to ensure that the light level is below 12 as that's the Hook mushroom's light value, and planting on nylium-based blocks like the Mushroom grass doesn't allow it to propagate either.

I think this bug is still happening in 7.1.2

Not working for me either in 7.1.2