WebSocket not using encryption despite the setting being enabled

Whenever I turn on the "Require Encrypted Websockets" setting and restart the game, it doesn't use encryption despite the setting being enabled.

In settings, the game appears as though the option is toggled on, however when I connect the game to my custom WebSocket server program, the game is not requesting an encrypted connection. At first I thought this was the fault of my programming, but a packet capture reveals the game is not requesting the com.microsoft.minecraft.wsencrypt protocol during the initial handshake like it normally would when using encryption.

I can fix this by toggling the option off-on, but the fact that it appears to be on when it's not gives users a false sense of security.