Hello, I have build both LibreOffice Core 6.3 and the latest master version of the online repo from scratch. (This exists in the LibreOffice Online 6.3 branch as well.) Whenever I try to add an image into my document (either through Nextcloud or locally) it never appears, not even the outline. I don't know if I have file permissions set wrong or if I'm missing a dependency, but if I try to insert an image from Nextcloud, nothing happens in the terminal that loolwsd is running in. However, I get this error when adding an image from a local source:

kit-28090-28072 2019-07-31 20:23:11.268913 [ loolkit ] SIG   Fatal signal received: SIGABRT
Backtrace 28090:
/home/lool/libreoffice_online/online/loolforkit(_ZN7SigUtil13dumpBacktraceEv+0x64) [0x558356e4f544]
/home/lool/libreoffice_online/online/loolforkit(+0xbd6d2) [0x558356e506d2]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x12890) [0x7ff844282890]
/lib/x86_64-linux-gnu/libc.so.6(gsignal+0xc7) [0x7ff843ebde97]
/lib/x86_64-linux-gnu/libc.so.6(abort+0x141) [0x7ff843ebf801]
/home/lool/libreoffice_online/core/instdir/program/libvcllo.so(_ZN16SalUserEventList18DispatchUserEventsEb+0x38b) [0x7ff83c272bdb]
/home/lool/libreoffice_online/core/instdir/program/libvcllo.so(_ZN14SvpSalInstance7DoYieldEbb+0x39) [0x7ff83c35ab39]
/home/lool/libreoffice_online/core/instdir/program/libvcllo.so(+0x6ace42) [0x7ff83c2a2e42]
/home/lool/libreoffice_online/core/instdir/program/libvcllo.so(_ZN11Application7ExecuteEv+0x45) [0x7ff83c2a4d55]
/home/lool/libreoffice_online/core/instdir/program/libsofficeapp.so(+0x2c972) [0x7ff842236972]
/home/lool/libreoffice_online/core/instdir/program/libvcllo.so(_Z10ImplSVMainv+0x46) [0x7ff83c2ac0f6]
/home/lool/libreoffice_online/core/instdir/program/libsofficeapp.so(soffice_main+0x115) [0x7ff842261e75]
/home/lool/libreoffice_online/core/instdir/program/libsofficeapp.so(+0x695d1) [0x7ff8422735d1]
/home/lool/libreoffice_online/online/loolforkit(_Z10lokit_mainRKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEES6_S6_S6_S6_bbbb+0x31d4) [0x558356dfb134]
/home/lool/libreoffice_online/online/loolforkit(+0x59d7e) [0x558356decd7e]
/home/lool/libreoffice_online/online/loolforkit(main+0x174b) [0x558356dbdc1b]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xe7) [0x7ff843ea0b97]
/home/lool/libreoffice_online/online/loolforkit(_start+0x2a) [0x558356dbf5ea]
kit-28090-28072 2019-07-31 20:23:11.270229 [ loolkit ] SIG  SIGSYS trapped with code: 1 and context 140735785366976
kit-28090-28072 2019-07-31 20:23:11.270251 [ loolkit ] SIG   seccomp trapped signal, un-authorized sys-call: 62
Backtrace 28090:
/home/lool/libreoffice_online/online/loolforkit(_ZN7SigUtil13dumpBacktraceEv+0x64) [0x558356e4f544]
/home/lool/libreoffice_online/online/loolforkit(+0xad668) [0x558356e40668]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x12890) [0x7ff844282890]
/lib/x86_64-linux-gnu/libc.so.6(kill+0x7) [0x7ff843ebe187]
/home/lool/libreoffice_online/online/loolforkit(+0xbd6e0) [0x558356e506e0]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x12890) [0x7ff844282890]
/lib/x86_64-linux-gnu/libc.so.6(gsignal+0xc7) [0x7ff843ebde97]
/lib/x86_64-linux-gnu/libc.so.6(abort+0x141) [0x7ff843ebf801]
/home/lool/libreoffice_online/core/instdir/program/libvcllo.so(_ZN16SalUserEventList18DispatchUserEventsEb+0x38b) [0x7ff83c272bdb]
/home/lool/libreoffice_online/core/instdir/program/libvcllo.so(_ZN14SvpSalInstance7DoYieldEbb+0x39) [0x7ff83c35ab39]
/home/lool/libreoffice_online/core/instdir/program/libvcllo.so(+0x6ace42) [0x7ff83c2a2e42]
/home/lool/libreoffice_online/core/instdir/program/libvcllo.so(_ZN11Application7ExecuteEv+0x45) [0x7ff83c2a4d55]
/home/lool/libreoffice_online/core/instdir/program/libsofficeapp.so(+0x2c972) [0x7ff842236972]
/home/lool/libreoffice_online/core/instdir/program/libvcllo.so(_Z10ImplSVMainv+0x46) [0x7ff83c2ac0f6]
/home/lool/libreoffice_online/core/instdir/program/libsofficeapp.so(soffice_main+0x115) [0x7ff842261e75]
/home/lool/libreoffice_online/core/instdir/program/libsofficeapp.so(+0x695d1) [0x7ff8422735d1]
/home/lool/libreoffice_online/online/loolforkit(_Z10lokit_mainRKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEES6_S6_S6_S6_bbbb+0x31d4) [0x558356dfb134]
/home/lool/libreoffice_online/online/loolforkit(+0x59d7e) [0x558356decd7e]
/home/lool/libreoffice_online/online/loolforkit(main+0x174b) [0x558356dbdc1b]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xe7) [0x7ff843ea0b97]
/home/lool/libreoffice_online/online/loolforkit(_start+0x2a) [0x558356dbf5ea]

I don't know what I need to provide you guys but I'm willing to provide anything given you tell me what I should do.

Steps to reproduce:

1. Build Libreoffice Core and Online and get them running
2. Integrate with nextcloud
3. Make a new document
4. Attempt to add an image

What Should happen:
- An image should be added

What does happen:
- No image is added and the document is reset to the last saved state.