branch: libreelec-7.0 stable
file: http://LibreELEC.tv/packages/addons/service/tvheadend/source/bin/tv_grab_file
You must update the previous file to the one in the master branch to be able to enable the internal epg grabber that uses the settings of the tvheadend kodi addon.
Right now there is no default internal grabber available.
Regards.