WD TV Play can't see some files

I have a top folder with several subfolders on my PC, shared through Windows Media Player.  On the WD TV Play, I can browse to the top folder but only a couple of the subfolders are visible.  The others don’t appear at all.

Within those subfolders are mostly MKV files.  Here’s the info on one that is visible and works:

General
Unique ID : 279651273081943777212712953210620508627 (0xD262E046DFC445EAA6A8ABC7F5F279D3)
Complete name : J:\TV Shows\True Detective\true.detective.s01e01.720p.hdtv.x264-killers.mkv
Format : Matroska
Format version : Version 4 / Version 2
File size : 1.62 GiB
Duration : 59mn 42s
Overall bit rate : 3 896 Kbps
Encoded date : UTC 2014-01-13 05:25:35
Writing application : mkvmerge v6.0.0 (‘Coming Up For Air’) built on Jan 20 2013 10:28:01
Writing library : libebml v1.3.0 + libmatroska v1.4.0

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.1
Format settings, CABAC : Yes
Format settings, ReFrames : 5 frames
Codec ID : V_MPEG4/ISO/AVC
Duration : 59mn 42s
Bit rate : 3 434 Kbps
Width : 1 280 pixels
Height : 720 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 23.976 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.155
Stream size : 1.43 GiB (88%)
Writing library : x264 core 140 r2377 1ca7bb9
Encoding settings : cabac=1 / ref=5 / deblock=1:0:0 / analyse=0x3:0x113 / me=umh / subme=8 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=18 / lookahead_threads=3 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=2 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 / keyint=250 / keyint_min=23 / scenecut=40 / intra_refresh=0 / rc_lookahead=50 / rc=crf / mbtree=1 / crf=18.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
Language : English
Default : Yes
Forced : No
Matrix coefficients : BT.709

Audio
ID : 2
Format : AC-3
Format/Info : Audio Coding 3
Mode extension : CM (complete main)
Format settings, Endianness : Big
Codec ID : A_AC3
Duration : 59mn 42s
Bit rate mode : Constant
Bit rate : 384 Kbps
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 48.0 KHz
Bit depth : 16 bits
Compression mode : Lossy
Stream size : 164 MiB (10%)
Default : Yes
Forced : No

Here is the media info on a file whose subfolder is invisible.  WDTV Play isn’t event detecting it:

General
Unique ID : 116375843517172691761523170346619770870 (0x578D2C14347E33AB4B3261BC816E17F6)
Complete name : J:\TV Shows\Black Sails\black.sails.s01e01.720p.hdtv.x264-2hd.mkv
Format : Matroska
Format version : Version 4 / Version 2
File size : 1.94 GiB
Duration : 1h 4mn
Overall bit rate : 4 280 Kbps
Encoded date : UTC 2014-01-18 20:19:48
Writing application : mkvmerge v6.0.0 (‘Coming Up For Air’) built on Jan 20 2013 09:40:09
Writing library : libebml v1.3.0 + libmatroska v1.4.0

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.1
Format settings, CABAC : Yes
Format settings, ReFrames : 5 frames
Codec ID : V_MPEG4/ISO/AVC
Duration : 1h 4mn
Bit rate : 3 811 Kbps
Width : 1 280 pixels
Height : 720 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 23.976 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.172
Stream size : 1.73 GiB (89%)
Writing library : x264 core 140 r2377 1ca7bb9
Encoding settings : cabac=1 / ref=5 / deblock=1:0:0 / analyse=0x3:0x113 / me=umh / subme=8 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=6 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=2 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=50 / rc=crf / mbtree=1 / crf=18.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
Language : English
Default : Yes
Forced : No

Audio
ID : 2
Format : AC-3
Format/Info : Audio Coding 3
Mode extension : CM (complete main)
Format settings, Endianness : Big
Codec ID : A_AC3
Duration : 1h 4mn
Bit rate mode : Constant
Bit rate : 384 Kbps
Channel(s) : 6 channels
Channel positions : Front: L C R, Side: L R, LFE
Sampling rate : 48.0 KHz
Bit depth : 16 bits
Compression mode : Lossy
Stream size : 178 MiB (9%)
Default : Yes
Forced : No

Any idea why?

Nevermind, turns out some of the subfolders weren’t being shared to the Homegroup.  I have no idea why some were shared and some weren’t, but I manually shared the rest and it works.