Unable to read subtitle list

In fact, it is subtitled and can be read and played normally. What's going on here? FTP: /Subtitle empty/

C:\Program Files\MKVToolNix>mkvmerge.exe -i "F:\a.mp4"
文件 ｢F:\a.mp4｣: 容器: QuickTime/MP4
轨道 ID 0: audio (E-AC-3)
轨道 ID 1: video (HEVC/H.265/MPEG-H)
轨道 ID 2: audio (AAC)
附件 ID 0: 类型｢image/png｣，大小 2718769 字节, 文件名 ｢cover.png｣


ffmpeg.exe -i "F:\a.mp4"
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'F:\a.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    title           : 天才基本法[The Heart of Genius](2022)
    encoder         : MP4 Tags Editor @ nilaoda
    comment         : HDCTV original works.
    copyright       : HDCTV
  Duration: 00:45:34.13, start: 0.000000, bitrate: 3629 kb/s
  Stream #0:0[0x1](chi): Audio: eac3 (ec-3 / 0x332D6365), 48000 Hz, stereo, fltp, 96 kb/s (default)
    Metadata:
      handler_name    : Mandarin,DDP
      vendor_id       : [0][0][0][0]
    Side data:
      audio service type: main
  Stream #0:1[0x2](und): Video: hevc (Main) (hev1 / 0x31766568), yuv420p(tv), 3840x1608, 3325 kb/s, 25 fps, 25 tbr, 90k tbn (default)
    Metadata:
      handler_name    : 4
      vendor_id       : [0][0][0][0]
  Stream #0:2[0x3](chi): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 191 kb/s
    Metadata:
      handler_name    : Mandarin
      vendor_id       : [0][0][0][0]
  Stream #0:3[0x5](chi): Subtitle: mov_text (tx3g / 0x67337874), 0 kb/s (default)
    Metadata:
      handler_name    : 中文（简体）
  Stream #0:4[0x6](chi): Subtitle: mov_text (tx3g / 0x67337874), 0 kb/s
    Metadata:
      handler_name    : 中文（繁體）
  Stream #0:5[0x7](eng): Subtitle: mov_text (tx3g / 0x67337874), 0 kb/s
    Metadata:
      handler_name    : English
  Stream #0:6[0x0]: Video: png, rgb24(pc), 1080x1496 [SAR 1:1 DAR 135:187], 90k tbr, 90k tbn (attached pic)