Unknownreported this bug
Keep inv in dungeons doesn't work after enabling game rule for it in gamerule file and even editing inside the dungeon editor world and setting as /minecraft:gamerule etccc
Tried with 0 lives, 1 lives etc..
It worked fine for past 1 year, but with 1.21.5 new server i've started and setuped as did last time and still not working