Call "Append events to a tracker" api before rest channel issue

when i call

/conversations/{sessionId}/tracker/events 

before

/webhooks/rest/webhook

when the sessionId is new and the first time i call. the response of rest channel will always be “[]” and the next time i call rest channel will be normal. is this a bug or something? can any one help me. my rasa version is 1.10.10 and i deploy with rasax on a docker-compose way.