diff --git a/plexapi/myplex.py b/plexapi/myplex.py
index fe856f345..925a189f8 100644
--- a/plexapi/myplex.py
+++ b/plexapi/myplex.py
@@ -623,9 +623,7 @@ def sync(self, sync_item, client=None, clientId=None):
         }
 
         url = SyncList.key.format(clientId=client.clientIdentifier)
-        data = self.query(url, method=self._session.post, headers={
-            'Content-type': 'x-www-form-urlencoded',
-        }, params=params)
+        data = self.query(url, method=self._session.post, params=params)
 
         return SyncItem(self, data, None, clientIdentifier=client.clientIdentifier)
 
diff --git a/plexapi/sync.py b/plexapi/sync.py
index ce60ca9f8..53dc0636f 100644
--- a/plexapi/sync.py
+++ b/plexapi/sync.py
@@ -178,19 +178,19 @@ class MediaSettings(object):
             photoQuality (int): photo quality on scale 0 to 100.
             photoResolution (str): maximum photo resolution, formatted as WxH (e.g. `1920x1080`).
             videoResolution (str): maximum video resolution, formatted as WxH (e.g. `1280x720`, may be empty).
-            subtitleSize (int|str): unknown, usually equals to 0, may be empty string.
+            subtitleSize (int): subtitle size on scale 0 to 100.
             videoQuality (int): video quality on scale 0 to 100.
     """
 
     def __init__(self, maxVideoBitrate=4000, videoQuality=100, videoResolution='1280x720', audioBoost=100,
-                 musicBitrate=192, photoQuality=74, photoResolution='1920x1080', subtitleSize=''):
+                 musicBitrate=192, photoQuality=74, photoResolution='1920x1080', subtitleSize=100):
         self.audioBoost = plexapi.utils.cast(int, audioBoost)
         self.maxVideoBitrate = plexapi.utils.cast(int, maxVideoBitrate) if maxVideoBitrate != '' else ''
         self.musicBitrate = plexapi.utils.cast(int, musicBitrate) if musicBitrate != '' else ''
         self.photoQuality = plexapi.utils.cast(int, photoQuality) if photoQuality != '' else ''
         self.photoResolution = photoResolution
         self.videoResolution = videoResolution
-        self.subtitleSize = subtitleSize
+        self.subtitleSize = plexapi.utils.cast(int, subtitleSize) if subtitleSize != '' else ''
         self.videoQuality = plexapi.utils.cast(int, videoQuality) if videoQuality != '' else ''
 
     @staticmethod