Google Smart Home can't recognize "action.devices.commands.TimerStart" command - google-smart-home

Question

I'm integrating my sprinkler product with Google Smart Home. Everything works except that the "action.devices.commands.TimerStart" command cannot be recognized by Google smart home.
Below is my SYNC response:
"body": {
"requestId": "12486236378229063564",
"payload": {
"agentUserId": "Oliver",
"devices": [
{
"id": "AAAA-BBBB-CCCC-DDDD",
"type": "action.devices.types.SPRINKLER",
"traits": [
"action.devices.traits.Timer",
"action.devices.traits.StartStop"
],
"name": {
"name": "Front yard"
},
"willReportState": true,
"deviceInfo": {
"manufacturer": "ABC company",
"model": "ABC",
"hwVersion": "3.2",
"swVersion": "11.4"
},
"attributes": {
"maxTimerLimitSec": 86399
}
}
]
}
}
Below is the QUERY response:
"body": {
"requestId": "7683156339707030974",
"payload": {
"devices": {
"AAAA-BBBB-CCCC-DDDD": {
"status": "SUCCESS",
"online": true,
"isRunning": false,
"timerRemainingSec": -1
}
}
}
}
When I type or speak "Start Front yard" on Google home app, my backend server receives the following command, which is correct.
"payload": {
"commands": [
{
"devices": [
{
"id": "AAAA-BBBB-CCCC-DDDD"
}
],
"execution": [
{
"command": "action.devices.commands.StartStop",
"params": {
"start": true
}
}
]
}
]
}
But when I type or speak "Run Front yard for five minutes" on Google home app, my backend server still receives the same command (action.devices.commands.StartStop) as the above. What I expect to receive is "action.devices.commands.TimerStart" command. Can anyone pls help point out what I'm doing wrong?
I expect to receive the "action.devices.commands.TimerStart" instead of the "action.devices.commands.StartStop" command after typing or speaking "Run Front yard for five minutes" on Google smart home.