All my radio recordings are downloading as AAC LTP instead of AAC LC since around the 9th November. They won't play in iTunes.

options:
radiomode bestmodes hvfbest,hlshd
fileprefix <channel>-<nameshort><.senum><.episodeshort>_<pid>
metadata generic
attempts 3
refresh-exclude-groups-radio local

Seems to vary depending on the programme.

For example, 11th November Shipping forecast records as AAC LC
Money box "Vanguard founder John Bogle on revolutionising fund management." records as AAC LTP.

I don't get LTP for your example. You can provide more examples if you like, but it won't really make any difference. get_iplayer doesn't transcode files, so you get whatever the BBC provides. It would be a little surprising if they switched to LTP, though.

Here's another:

$ mediainfo *m4a
General
Complete name                            : BBC_Radio_4-Open_Country.Snowdonia_Marathon_b081t6xf.m4a
Format                                   : MPEG-4
Format profile                           : Apple audio with iTunes info
Codec ID                                 : M4A  (isom/iso2)
File size                                : 56.1 MiB
Duration                                 : 24 min 23 s
Overall bit rate mode                    : Constant
Overall bit rate                         : 322 kb/s
Album                                    : Open Country
Album/Performer                          : BBC Radio
Track name                               : Open Country: Snowdonia Marathon
Grouping                                 : Factual,Science & Nature,Nature & Environment
Performer                                : BBC Radio 4
Composer                                 : BBC iPlayer
Genre                                    : Factual
ContentType                              : Music
Recorded date                            : UTC 2016-11-10 15:00:00
Encoded date                             : UTC 1904-01-01 00:00:00
Tagged date                              : UTC 2016-11-14 14:43:50
Writing application                      : Lavf57.56.100
Copyright                                : 2016 British Broadcasting Corporation, all rights reserved
Cover                                    : Yes
Comment                                  : Helen Mark meets the runners, organisers and volunteers behind Snowdonia Marathon.

Audio
ID                                       : 1
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LTP
Codec ID                                 : 40
Duration                                 : 24 min 23 s
Bit rate mode                            : Constant
Bit rate                                 : 320 kb/s
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Sampling rate                            : 64.0 kHz
Frame rate                               : 62.500 FPS (1024 spf)
Compression mode                         : Lossy
Stream size                              : 55.8 MiB (100%)
Language                                 : English
Default                                  : Yes
Alternate group                          : 1
Encoded date                             : UTC 1904-01-01 00:00:00
Tagged date                              : UTC 1904-01-01 00:00:00[/code

That appears to be a problem introduced with ffmpeg 3.2, but it only seems to affect the default DASH streams. For now, either roll back to an earlier version of ffmpeg or try --radiomode=haf.

EDIT: The streams haven't changed, but the behaviour of ffmpeg 3.2 in re-muxing is now different.

Thanks user-2, using "haf" fixed it!

This issue seems to have disappeared with ffmpeg 3.2.1, so no longer need to use --radiomode=haf . If you still see the same problem with ffmpeg 3.2.1 or higher, post an example here and I'll check it out.