When you're in creative mode and try to mine blocks with the mace, it doesn't mine the blocks or do anything. When I'm using the mace in survival mode and try to mine blocks it works just fine.
How to reproduce
Start off by obtaining the mace, you can do that by going to data packs in world options and enabling the 1.21 experimental data packs.
Then go to creative mode and search for the mace and try to mine blocks using it.
This behavior is consistent with other melee weapons (sword, trident).