REST API does not accept some commands/options

Hello, this is my first post and I expect this is the right place to write it.

I have a couple of Samsung Windfree AC splits. The ST REST API is working well but I can’t change some options, for instance the “Quiet” mode.
This mode can be set with the remote control and also with the Android ST APP.
But when I try with the REST API, (with postman), the command does nothing.

I have tried with the following command:
{“commands”:[{“component”:“main”,“capability”:“custom.airConditionerOptionalMode”,“command”:“setAcOptionalMode”,“arguments”:[“quiet”]}]}
and also this one:
{“commands”:[{“component”:“main”,“capability”:“execute”,“command”:“execute”,“arguments”:[“mode/convenient/vs/0”, {“x.com.samsung.da.mode.convenient”:[“Quiet”]}]}]}
I have also tried the “quiet” and “Quiet” combinations.

The json response for the commands issued is “ACCEPTED” instead of “COMPLETED” which is the normal response obtained for other modes.

I assume that the reason for this behaviour is that the “supportedAcOptionalMode” obtained with the /status does not include the ‘quiet’ mode (it has “off”, “sleep”, “speed”, “windFree”, and “windFreeSleep”)

Another curious thing is that the /status returns the “acOptionalMode” = “quiet” when it is sent with the remote or the ST Android APP. but not when it is sent with API calls.

Does anybody know if this is a limitation of my devices? Or the API? Or the firmware version of my recently purchased equipments (AR**TXFCAWKNEU)?

Your help is greatly appreciated,
Thanks
Javier