Masons house loot is unused since no masons house that generates in any type of village includes any chest, the loot can be given to the player or inserted on a chest using the loot command with this inserted on it:
“chests/village/village_mason"
MCPE-178165
Masons house loot is unused
Open
4
(Unassigned)
1168940
Confirmed
Multiple
loot-table, structure, structure-generation, unused, vanilla-parity, world-generation
1.20.60.25 Preview, 1.20.60.24 Preview, 1.20.51 Hotfix, 1.21.0.22 Preview, 1.21.0.20 Preview, ..., 1.21.0.23 Preview, 1.20.80, 1.21.0.24 Preview, 1.21.10.20 Preview, 1.20.81 Hotfix
Retrieved
Technically the savanna mason's house should contain a chest using this loot table, but the savanna mason's house appears to never generate. This appears to be the real issue.