I am not seeing any issues. Perhaps another plugin is blocking it? If possible, type /nodecay log in chat, wait a couple of cycles (5-10 minutes) and paste some of the resulting log from nodecay (in oxide log):
(17:09:14) | [Oxide] 17:09 [Info] [NoDecay] floor owner 7656119830@#04196 has NoDecay permission!
(17:09:14) | [Oxide] 17:09 [Info] [NoDecay] NoDecay checking for block damage to floor
(17:09:14) | [Oxide] 17:09 [Info] [NoDecay] NoDecay checking for local cupboard.
(17:09:14) | [Oxide] 17:09 [Info] [NoDecay] CheckCupboardBlock: Checking for cupboard connected to stone floor.
(17:09:14) | [Oxide] 17:09 [Info] [NoDecay] CheckCupboardBlock: Block owned by cupboard!
(17:09:14) | [Oxide] 17:09 [Info] [NoDecay] Decay (stone) before: 0.8299426 after: 0
(17:09:14) | [Oxide] 17:09 [Info] [NoDecay] Decay (floor) before: 0.8299426 after: 0, item health 500