Problem with Radio Downloads

[Budge]

I have a number of radio programmes set to record in my pvr which runs 
nightly.  Since 17 January the resulting .m4a files will not play on my 
usual Linn DS rendering devices.

I am trying to identify the source of the problem.
I see nothing remarkable to me in the --verbose output from GiP.  I have 
this in a text file of 150+ lines.  Can I post it here?

So far the only difference between an m4a file of similar length which 
plays and one which doesn't is that when I look at them with 
AtomicParsley and ffprobe I get the messages which I have extracted from 
the output for brevity here:


NON Playing Files I get:-
AtomicParsley version: 0.9.6 (utf8)
------------------------------------------------------
Movie duration: 823.275 seconds (13:43.28) - 320.00* kbp/sec bitrate 
(*=approximate)
Low-level details. Total tracks: 1
Trk  Type  Handler                    Kind  Lang  Bytes
1    soun  SoundHandler               mp4a  eng   32930987
      320.00 kbp/s  MPEG-4 Unknown profile: 0x0    channels: (2)

FFprobe:
...Duration: 00:27:50.40, start: 0.000000, bitrate: 321 kb/s
     Stream #0:0(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, 
fltp, 320 kb/s (default)
     Metadata:
       handler_name    : SoundHandler
     Stream #0:1: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 
150x84 [SAR 72:72 DAR 25:14], 90k tbr, 90k tbn, 90k tbc


Files which DO PLAY I get:-

AtomicParsley version: 0.9.6 (utf8)
------------------------------------------------------
Movie duration: 1996.800 seconds (33:16.80) - 320.00* kbp/sec bitrate 
(*=approximate)
Low-level details. Total tracks: 1
Trk  Type  Handler                    Kind  Lang  Bytes
1    soun  SoundHandler               mp4a  eng   79872007
      320.00 kbp/s  MPEG-4 AAC Low Complexity/LC Profile    channels: [2]



FFprobe:

  Duration: 00:33:16.80, start: 0.000000, bitrate: 321 kb/s
     Stream #0:0(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, 
stereo, fltp, 320 kb/s (default)
     Metadata:
       handler_name    : SoundHandler
     Stream #0:1: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 
150x84 [SAR 72:72 DAR 25:14], 90k tbr, 90k tbn, 90k tbc

The difference seems to be in the absence of the LC Profile.  Can 
somebody please tell me what this means and where this comes from.  Is 
the problem likely to be from my machine, which seems probable, in which 
case where should I look?