Couchbase Lite iOS Bad Data Encoding Error

I’m using Couchbase Lite on a mobile ionic framework project. I create a photo from the device camera in a base64 data URL. I put that into a document _attachments property and it works great on Android when I PUT the doc into CouchBase, but gives a Bad Data Encoding error on iOS.

doc is a JSON object.
                    doc._attachments = {
                        "inPhoto" : {
                            content_type : "image/jpeg",
                            data : imageData // base64 encoded jpeg image from device camera shot.
                        }
                    }
           
                query = encodeURI(COUCHBASEURL + dbName + SLASH + docId + '?rev=' + doc._rev);
                $http.put(query, doc).success(function(data, status, headers, config) {
                    success(data, status, headers, config);
                }).error(function(data, status, headers, config) {
                    fail(data, status, headers, config);
                });

Hits the fail() line with the error: BAD DATA ENCODING

Anyone else seen this or know what might be going on?