5th Support Slot not working for Gelid Palm with Way of the Stonefist

I upgraded my Thunderfist Utility Wraps with a Perfect Jewellers Orb to open the fifth support gem slot and any attempt to socket it is met with "this support can't be socketed into this skill" even though I'm able to use the gem on any of the 4 other slots. Unallocating Way of the Stonefist allows me to use the 5th slot, but once the ascendancy node is reallocated, the gem disappears until the gauntlets are removed.
TLDR 5th Support Slot from Perfect Jewllers Orb on Unique Gauntlet Skills doesn't work with Way of the Stonefist.