Inverter Control API for Modify Present allows 2nd charge times to be specified but doesn't work

I intend to control my battery charing times via API - I see in the Modify Settings API that a second start/end time can be specified, however this doesn’t appear in the UI and returns this error message if I try and set a time. Is it supported?
“success”: false,
“message”: “Inverter Timeout”

Get Settings List shows the ID’s to be 28 & 29:-
{“id”: 28,
“name”: “AC Charge 2 Start Time”,
“validation”: “Value format should be HH:mm. Use correct time range for hour and minutes”,
“validation_rules”: [
“date_format:H:i”
]},
{“id”: 29,
“name”: “AC Charge 2 End Time”,
“validation”: “Value format should be HH:mm. Use correct time range for hour and minutes”,
“validation_rules”: [
“date_format:H:i”]},

AC3 hardware?

Doesn’t support multiple charge times, hardware limitations.

What batteries are you using - and inverter…

Are you sure you are using the correct API’s ?

there isn’t a second charge slot available as far as I’m aware on AC3 Inverters