Error recording an RTSP stream without transcoding - ffmpeg

Question

I'm trying to use FFmpeg to record RTSP streams from several security cameras. I have been successfully transcoding each stream for months now, but since this requires considerable CPU power, I'd like to simply copy each stream to disk in it's original H.264 format.
Whenever I try this, I receive and error similar to this (the "current" value varies):
Non-monotonous DTS in output stream 0:0; previous: 0, current: -62743;
I've stripped most of the options I was using, although I really do want to keep -xerror so that FFmpeg quits when it encounters an error:
ffmpeg.exe -xerror -i rtsp://admin:admin#192.168.1.135 -an -vcodec copy test.mp4
And I still get this:
ffmpeg version 3.3.3 Copyright (c) 2000-2017 the FFmpeg developers
built with gcc 7.1.0 (GCC)
configuration: --enable-gpl
--enable-version3 --enable-cuda --enable-cuvid --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-zlib
libavutil 55. 58.100 / 55. 58.100
libavcodec 57. 89.100 / 57. 89.100
libavformat 57. 71.100 / 57. 71.100
libavdevice 57. 6.100 / 57. 6.100
libavfilter 6. 82.100 / 6. 82.100
libswscale 4. 6.100 / 4. 6.100
libswresample 2. 7.100 / 2. 7.100
libpostproc 54. 5.100 / 54. 5.100
[udp # 0000000002533b60] 'circular_buffer_size' option was set but it is not supported on this build (pthread support is required)
[udp # 0000000000ec97a0] 'circular_buffer_size' option was set but it is not supported on this build (pthread support is required)
Input #0, rtsp, from 'rtsp://admin:admin#192.168.1.135': Metadata:
title : RTSP Session/2.0 Duration: N/A, start: 0.837144, bitrate: N/A
Stream #0:0: Video: h264 (High), yuvj420p(pc, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 7 fps, 25 tbr, 90k tbn, 14 tbc Output
#0, mp4, to 'test.mp4': Metadata:
title : RTSP Session/2.0
y encoder : Lavf57.71.100
Stream #0:0: Video: h264 (High) ([33][0][0][0] / 0x0021), yuvj420p(pc, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 7 fps, 25 tbr, 90k tbn, 90k tbc
Stream mapping: Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
[mp4 # 00000000036b8340] Non-monotonous DTS in output stream 0:0; previous: 0, current: -62743; aborting.
Conversion failed!
Can anyone explain what the problem is and/or suggest the appropriate flags to handle this?