MCEBuddy/FFmpeg is trying to use your graphics driver hardware encoding:
-c:v hevc_nvenc
and your graphics driver is failing:
2019-03-19T21:07:32 MCEBuddy.AppWrapper.FFmpeg → [AVHWDeviceContext @ 000002ea637a3740] Failed to create Direct3D device
2019-03-19T21:07:32 MCEBuddy.AppWrapper.FFmpeg → Device creation failed: -1313558101.
Try to update your graphics driver or downgrade depending on your version to a stable version. See the Hardware FAQ page for recommendations on drivers versions are reported stable.
Alternatively you can disabled hardware encoding on the Conversion Task → Expert Settings page
It may also help if there was someone logged into your server, I saw another error from Windows, it may not apply to Server 2019, but you can see if it helps (graphics drivers behave different when someone is logged in v/s not logged in for some Windows versions)
ERROR> 2019-03-19T21:07:32 → StartAppWithAdminPrivilegesFromNonUISession WTSQueryUserToken failed (No logged on users) with error 1008. An attempt was made to reference a token that does not exist.