diff --git a/src/controllers/user.js b/src/controllers/user.js
index 1d7414695a..986b5d36da 100644
--- a/src/controllers/user.js
+++ b/src/controllers/user.js
@@ -40,7 +40,6 @@ api.marketBuy = function(req, res, next){
   })
 }
 
-
 /*
   ------------------------------------------------------------------------
   Tasks
@@ -65,12 +64,15 @@ api.verifyTaskExists = function(req, res, next) {
 };
 
 function deleteTask(user, task) {
-  user[task.type+'s'].id(task.id).remove();
+  var i = _.findIndex(user[task.type+'s'], {id:task.id});
+  if (~i) {
+    user[task.type+'s'].splice(i, 1)
+    //user.markModified(task.type+'s')
+  }
 };
 
 function addTask(user, task) {
   task = helpers.taskDefaults(task);
-  task._id = task.id;
   user[task.type+'s'].unshift(task);
   return task;
 }
diff --git a/src/models/challenge.js b/src/models/challenge.js
index 6ad5725168..497c9093dd 100644
--- a/src/models/challenge.js
+++ b/src/models/challenge.js
@@ -2,7 +2,6 @@ var mongoose = require("mongoose");
 var Schema = mongoose.Schema;
 var helpers = require('habitrpg-shared/script/helpers');
 var _ = require('lodash');
-var TaskSchema = require('./task').schema;
 var Group = require('./group').model;
 
 var ChallengeSchema = new Schema({
@@ -10,10 +9,10 @@ var ChallengeSchema = new Schema({
   name: String,
   shortName: String,
   description: String,
-  habits: [TaskSchema],
-  dailys: [TaskSchema],
-  todos: [TaskSchema],
-  rewards: [TaskSchema],
+  habits: [Schema.Types.Mixed],
+  dailys: [Schema.Types.Mixed],
+  todos: [Schema.Types.Mixed],
+  rewards: [Schema.Types.Mixed],
   leader: {type: String, ref: 'User'},
   group: {type: String, ref: 'Group'},
   timestamp: {type: Date, 'default': Date.now},
@@ -31,6 +30,11 @@ ChallengeSchema.virtual('tasks').get(function () {
 // FIXME this isn't always triggered, since we sometimes use update() or findByIdAndUpdate()
 // @see https://github.com/LearnBoost/mongoose/issues/964
 ChallengeSchema.pre('save', function(next){
+  // @see comment in user.js pre(save)
+  this.markModified('habits');
+  this.markModified('dailys');
+  this.markModified('todos');
+  this.markModified('rewards');
   this.memberCount = _.size(this.members);
   next()
 })
@@ -39,11 +43,11 @@ ChallengeSchema.methods.toJSON = function(){
   var doc = this.toObject();
   doc.memberCount = doc.members ? _.size(doc.members) : doc.memberCount; // @see pre('save') comment above
   doc._isMember = this._isMember;
-  _.each(['habits','dailys','todos','rewards'], function(type){
-    _.each(doc[type],function(task){
-      task.id = task._id;
-    })
-  })
+//  _.each(['habits','dailys','todos','rewards'], function(type){
+//    _.each(doc[type],function(task){
+//      task.id = task._id || task.id;
+//    })
+//  })
   return doc;
 }
 
diff --git a/src/models/user.js b/src/models/user.js
index 48ff54f540..df2396e6b3 100644
--- a/src/models/user.js
+++ b/src/models/user.js
@@ -8,7 +8,6 @@ var mongoose = require("mongoose");
 var Schema = mongoose.Schema;
 var helpers = require('habitrpg-shared/script/helpers');
 var _ = require('lodash');
-var TaskSchema = require('./task').schema;
 
 // User Schema
 // -----------
@@ -191,10 +190,10 @@ var UserSchema = new Schema({
 
   challenges: [{type: 'String', ref:'Challenge'}],
 
-  habits: [TaskSchema],
-  dailys: [TaskSchema],
-  todos: [TaskSchema],
-  rewards: [TaskSchema],
+  habits: [Schema.Types.Mixed],
+  dailys: [Schema.Types.Mixed],
+  todos: [Schema.Types.Mixed],
+  rewards: [Schema.Types.Mixed],
 
 }, {
   strict: true,
@@ -209,12 +208,11 @@ UserSchema.methods.toJSON = function() {
   doc.filters = {};
   doc._tmp = this._tmp; // be sure to send down drop notifs
 
-  // TODO why isnt' this happening automatically given the TaskSchema.methods.toJSON above?
-  _.each(['habits','dailys','todos','rewards'], function(type){
-    _.each(doc[type],function(task){
-      task.id = task._id;
-    })
-  })
+//  _.each(['habits','dailys','todos','rewards'], function(type){
+//    _.each(doc[type],function(task){
+//      task.id = task._id || task.id;
+//    })
+//  })
 
   return doc;
 };
@@ -229,7 +227,16 @@ UserSchema.virtual('tasks').get(function () {
  // Custom setter/getter virtuals?
 
 UserSchema.pre('save', function(next) {
-  //this.markModified('tasks');
+  // I finally figured out when markModified() is required - when using Schema.Type.Mixed or Array. Let's say you
+  // have `tasks: [{text:String, notes:String}]`. Because it's a defined schema, Mongoose can track attribute changes.
+  // But if you have `tasks: [Schema.Types.Mixed]`, Mongoose can't track underlying attr changes - only top-level changes
+  // (via splice(), push/unshift(), etc). Adding a workaround here, which is very inefficient - we'll want to find
+  // each location where a task attr is modified and use `user.markModified(task.type+'s')`
+  // (@see https://github.com/HabitRPG/habitrpg/issues/1711#issuecomment-27626467)
+  this.markModified('habits');
+  this.markModified('dailys');
+  this.markModified('todos');
+  this.markModified('rewards');
 
   if (!this.profile.name) {
     var fb = this.auth.facebook;