Fixed. When an image is updated in the server and app folder is refreshed, the thumbnail does not change and it is not updated

src/com/owncloud/android/datamodel/FileDataStorageManager.java

@@ -300,6 +300,7 @@ public class FileDataStorageManager {
             cv.put(ProviderTableMeta.FILE_PUBLIC_LINK, file.getPublicLink());
             cv.put(ProviderTableMeta.FILE_PERMISSIONS, file.getPermissions());
             cv.put(ProviderTableMeta.FILE_REMOTE_ID, file.getRemoteId());
+            cv.put(ProviderTableMeta.FILE_UPDATE_THUMBNAIL, file.needsUpdateThumbnail());
 
             boolean existsByPath = fileExists(file.getRemotePath());
             if (existsByPath || fileExists(file.getFileId())) {

src/com/owncloud/android/operations/SynchronizeFolderOperation.java

@@ -33,6 +33,7 @@ import org.apache.http.HttpStatus;
 import android.accounts.Account;
 import android.content.Context;
 import android.content.Intent;
+import android.util.Log;
 //import android.support.v4.content.LocalBroadcastManager;
 
 import com.owncloud.android.datamodel.FileDataStorageManager;
@@ -323,9 +324,11 @@ public class SynchronizeFolderOperation extends RemoteOperation {
      *  @return                 'True' when any change was made in the local data, 'false' otherwise
      */
     private void synchronizeData(ArrayList<Object> folderAndFiles, OwnCloudClient client) {
+        Vector<OCFile> mImageFiles = mStorageManager.getFolderImages(mLocalFolder);
+
         // get 'fresh data' from the database
         mLocalFolder = mStorageManager.getFileByPath(mLocalFolder.getRemotePath());
-        
+
         // parse data from remote folder 
         OCFile remoteFolder = fillOCFile((RemoteFile)folderAndFiles.get(0));
         remoteFolder.setParentId(mLocalFolder.getParentId());
@@ -372,6 +375,15 @@ public class SynchronizeFolderOperation extends RemoteOperation {
                 if (remoteFile.isFolder()) {
                     remoteFile.setFileLength(localFile.getFileLength()); 
                         // TODO move operations about size of folders to FileContentProvider
+                } else if (mRemoteFolderChanged && remoteFile.isImage()) {
+                    // If image has been updated on the server, set for updating the thumbnail
+                    for (OCFile fileImage: mImageFiles) {
+                        if (remoteFile.getRemoteId().equals(fileImage.getRemoteId()) &&
+                                remoteFile.getModificationTimestamp() > fileImage.getModificationTimestamp()) {
+                            remoteFile.setNeedsUpdateThumbnail(true);
+                            Log.d(TAG, "Image " + remoteFile.getFileName() + " updated on the server");
+                        }
+                    }
                 }
                 remoteFile.setPublicLink(localFile.getPublicLink());
                 remoteFile.setShareByLink(localFile.isShareByLink());