keepInventory doesn't go false

[kastanomata]

In my newly-created server, keepInventory is always set to true, no matter what I do: I've tried using the dashboard command, or even opping myself and typing it in the game chat. I have no plugins, it's a completely vanilla 1.15 Vanilla server
Help me out, please: how do I set keepInventory to false?

[AttendantFox]

Double check that you're running this command ingame:

/gamerule keepInventory false

This applies only to the world you're in. 

[kastanomata]

I tried doing that with the console I found in the dashboard and with my account, after being opped using the same console. Other /gamerule commands work, I don't know what is happening here