Unable to save multi taxonomy field value via RESTapi

I have a very peculiar problem. I am updating a list with a multi-value taxonomy field via REST on a SharePoint hosted app. Other list fields are being updated apart from this one multi-value taxonomy field. No error is being thrown. Here is my code

var body = {
  "Title": "Title of list item",
  "i2eb836f74154a63a65bdddfefd7e5e5": "-1;#Biosciences|f33e6f09-29ed-4d2f-a232-3c1da3c84710;#-1;#Clinical|589af719-fd79-4b44-ab4c-03cf9247f2c5;#",
  "__metadata": {
     "type": "SP.Data.ListTitleListItem"
  }
};

$http({
        url: appUrl + '/_api/SP.AppContextSite(@target)/web/Lists/getByTitle('ListTitle')/Items?@target='hostUrl',
        method: "POST",
        headers: {
            "Accept": "application/json;odata=verbose",
            "Content-Type": "application/json;odata=verbose",
            "Content-Length": body.length,
            "X-RequestDigest": formDigestValue
        },
        data: JSON.stringify(body)
   })

Where

'i2eb836f74154a63a65bdddfefd7e5e5'

is the internal name for the hidden note field corresponding to the multi-value taxonomy field and the string below

"-1;#Biosciences|f33e6f09-29ed-4d2f-a232-3c1da3c84710;#-1;#Clinical|589af719-fd79-4b44-ab4c-03cf9247f2c5;#"

represents the values that I'm trying to insert into this field. I created this field via visual studio and I am able to insert values into it if I update the list item from the SharePoint UI. What perturbs me is that the above code works perfectly for a multi-value taxonomy field I created directly from the SharePoint UI. Has anyone experienced this before, and if so, how did you resolve it?