I've been trying to get screen capture in kdenlive running on my desktop which has multiple monitors. FYI, it works fine on my laptop. When I try to do a screen grab I get the following error message below the monitor:

Capture crashed please check your parameters.

The parameters are:
ffmpeg version 3.4.4-0ubuntu0.18.04.1 Copyright (c) 2000-2018 the FFmpeg developers built with gcc 7 (Ubuntu 7.3.0-16ubuntu3) configuration: --prefix=/usr --extra-version=0ubuntu0.18.04.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared libavutil 55. 78.100 / 55. 78.100 libavcodec 57.107.100 / 57.107.100 libavformat 57. 83.100 / 57. 83.100 libavdevice 57. 10.100 / 57. 10.100 libavfilter 6.107.100 / 6.107.100 libavresample 3. 7. 0 / 3. 7. 0 libswscale 4. 8.100 / 4. 8.100 libswresample 2. 9.100 / 2. 9.100 libpostproc 54. 7.100 / 54. 7.100
Invalid MIT-MAGIC-COOKIE-1 key[x11grab @ 0x55cfe1c3d760] Cannot open display :0.0+1440.1600, error 1. :0.0+1440.1600: Input/output error

I suspect this is because it is trying to use screen 0, when my screens are on 1. As an example, I can record fine just using ffmpeg on 1.0. The following work fine:

ffmpeg -video_size 1024x768 -framerate 25 -f x11grab -i :1.0+100,200 output.mp4

How can I get kdenlive to use 1.0 instead of 0.0? I've been playing around with this for 3 days and can't seem to get it to budge from 0.0?