@vladcampos It sounds like maybe some URLs changed that are interfering with the cross-posting? Show cross-posting tries to find the feeds that match the currently selected blog, so if the new blog has no feeds and cross-posting accounts enabled, that could explain it. If you switch to the previous blog, does it work?
@help There's no social networks connected on the new blog. The problem is happening on the old blog (vladcampos.com), where everything was working fine before.