Ajax Post not working

I created a list from appweb to hostweb and the list url is without "lists/" I then trying to use ajax call post on my startsite (not from the app) but i get following error: 400 bad request x.support.cors.e.crossDomain.send

SharePoint Online

   function saveSelectedAnswer(selectedAnswer) {
        var requestUri = _spPageContextInfo.webAbsoluteUrl + "/_api/web/lists/getByTitle('PollUserData')/items/";
        var pollData = {
            __metadata: {
                "type": "SP.Data.PollUserDataListItem"
            },
            Title: 'test',
            UserID: userGuid, //text
            Question: allQuestionsArray[0].Question, //text
            QuestionAnswers: allQuestionsArray[0].Answers, //text
            Answer: selectedAnswer,  //text
            QuestionID: allQuestionsArray[0].ID //number
                //Check field types if error
        };
        var requestBody = JSON.stringify(pollData);
        var requestHeaders = {
            "ACCEPT": "application/json;odata=verbose",
            "X-RequestDigest": $("#__REQUESTDIGEST").val(),
        }
        $.ajax({
            url: requestUri,
            type: "Post",
            async: false,
            contentType: "application/json;odata=verbose",
            data: requestBody,
            headers: requestHeaders,
            success: function() {
                console.log("data saved");
                $("#weeklyPollContainer").hide();
                showLoader();
            },
            error: function(xhr, thrownError) {
                alert("Error save answers " + xhr.status + " " + thrownError);
            }
        });
    }