other: 0.168
semantic: 0.134
device: 0.117
boot: 0.106
debug: 0.091
graphic: 0.082
PID: 0.056
performance: 0.052
vnc: 0.046
socket: 0.041
permissions: 0.039
files: 0.030
network: 0.027
KVM: 0.012
debug: 0.793
files: 0.051
other: 0.038
boot: 0.032
device: 0.019
semantic: 0.012
PID: 0.011
network: 0.010
socket: 0.010
performance: 0.007
KVM: 0.006
vnc: 0.005
permissions: 0.004
graphic: 0.003

Converting qcow2 to vmdk on MacOSX results in a non-bootable image

When using qemu-img convert -O vmdk  with version 3.1.0 or 4.0.0 on OSX (10.14.3) with a qcow2 image  (https://cloud-images.ubuntu.com/bionic/20190703/bionic-server-cloudimg-amd64.img), the resulting image is not bootable.

Running the same command on Ubuntu 18.04 results in a bootable image as expected

Try the solutions in 1828508 ( -o  adapter_type=lsilogic,subformat=monolithicFlat)  1776920 ( -S 0 ) do not work either

What other steps can I take to troubleshoot?

Does the problem happen only when the image is on APFS? when the destination is on APFS? Neither? Try to see if it's the filesystem. Use OSX to convert images on a non-APFS formatted external drive to see if that improves your luck.

I'm assuming this is a duplicate of 1776920 which is still open because we have no OSX developers willing or able to debug this problem.