FFMPEG command not working on MP4 files as expected - ffmpeg

Question

I am trying to set the output time offset for mp4 file.
ffmpeg -ss 13.554000 -i input.mp4 -c copy -t 10 -output_ts_offset 13.554000 output.mp4
This code works for WEBM file as expected but not for MP4.
In webm it delays start time of video to the specified timestamp and duration is 23.554 but in mp4 it just cuts the video, start time is set to 0 and duration is 10
Cannot find what is problem.
ffmpeg -ss 12.960000 -i v.mp4 -c copy -t 10 -output_ts_offset 12.960000 output.mp4
ffmpeg version git-2019-12-26-b0d0d7e Copyright (c) 2000-2019 the FFmpeg developers
built with gcc 9.2.1 (GCC) 20191125
configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig
--enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb
--enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora
--enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp
--enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis
--enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid
--enable-libaom --enable-libmfx --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth
--enable-libopenmpt --enable-amf
libavutil 56. 37.100 / 56. 37.100
libavcodec 58. 65.100 / 58. 65.100
libavformat 58. 35.101 / 58. 35.101
libavdevice 58. 9.101 / 58. 9.101
libavfilter 7. 69.101 / 7. 69.101
libswscale 5. 6.100 / 5. 6.100
libswresample 3. 6.100 / 3. 6.100
libpostproc 55. 6.100 / 55. 6.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'v.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
creation_time : 1970-01-01T00:00:00.000000Z
encoder : Lavf53.24.2
Duration: 00:00:29.57, start: 0.000000, bitrate: 1421 kb/s
Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 1032 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
Metadata:
creation_time : 1970-01-01T00:00:00.000000Z
handler_name : VideoHandler
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, 5.1, fltp, 383 kb/s (default)
Metadata:
creation_time : 1970-01-01T00:00:00.000000Z
handler_name : SoundHandler
Output #0, mp4, to 'output.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf58.35.101
Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=2-31, 1032 kb/s, 25 fps, 25 tbr, 12800 tbn, 12800 tbc (default)
Metadata:
creation_time : 1970-01-01T00:00:00.000000Z
handler_name : VideoHandler
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, 5.1, fltp, 383 kb/s (default)
Metadata:
creation_time : 1970-01-01T00:00:00.000000Z
handler_name : SoundHandler
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
frame= 250 fps=0.0 q=-1.0 Lsize= 1687kB time=00:00:09.99 bitrate=1382.7kbits/s speed=2.21e+03x
video:1212kB audio:468kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.408804%```