Somebody else on the forum mentioned this.
I am assuming you are referring to the BBC iPlayer App ?
Have you tried the basic stuff, like deleting the iPlayer App then re install the App again from the box Apps Store.
Reboot both your NowTV box and Router by switching the power off for about one minute.
Try a forced software update on the box by following these instructions.
Start by pressing your NOW TV remote control buttons in this order:
Fast Forward x3
Select the Update Software option that appears on the next screen.
Press OK, even if you already have the latest version.
Out of curisoity what NowTV device are you using, where my NowTV 4K smart box seems to be working fine with the BBC iPlayer App ?
Should you have the NowTV Freeview smart box and the BBC over the air TV channels are not showing then maybe try a fresh re scan of the TV channels in the box menu settings.
Also use this website tool to check if there is no maintenance work on your local area transmitter or relay repeater that might be causing the temporary loss of TV signal for the BBC Freeview TV stations.