Press the HOME button. Select SETTINGS and then System Settings.
Then in Power Management set Power Saving in Standby to ‘Off’. When set to On the product will not supply the loop through aerial signal to your TV. (Page GB24 of my copy of the manual.)
Humax have to default this setting to ‘On’ because of UK consumer electronics power usage legislation. Your LG recorder probably pre-dated when the legislation came out.
Unless you are in a weak signal area a cheaper option, and the ‘green’ option, is to split the aerial lead with one split going to the TV and the other going to the FVP-4000T.