Node title get deleted when saving a translation of the node
Do you want to manage your content type translation at node level or field level ? You can have a mix of both on the same site if needed, for different content types, but don't mix up within a content type.

If you choose "basic" node translation for content type A, you won't need the Title module, so if it's enabled/in use for content type B, just don't "replace" (admin/structure/types/manage/content_type_A/fields/replace/title) the built in node title of A by a field.

Then when you translate a node from node/xxx/translate then node/add/content_type_A?translation=xxx&amp;target=lang , everything should be ok. 

Read also Gábor Hojtsy explanations which are still valuable about translation settings, or Randy Fay Field translation: First steps