Why Can't I Set Luminosity To 15?

I'm trying to make a block that glows and emits light similar to a (Jack o Lantern or Glow Stone) and the Light Level for those are around 15, however for mcreator version 1.8.0 Luminosity maxes out at 1.

I've seen tutorials where people set Luminosity on older version of mcreator to 15 and above, but I can't do it in this version, what gives?

Can someone please help me with a work around or let me know if theres a new way of doing this?

Otherwise if this is a bug, well then this is another feature out of many that are having issues in the newer version.