Hi I had the same problem, although in a different environment (I’m currently using a GVM container) and managed to solve it with your steps, but there is a small mistake (or at least the correction below worked for me):
Instead of:
sudo runuser -u _gvm – gvmd --modify-setting 78eceaec-3385-11ea-b237-28d24461215b --value dabd2710-aebd-4048-a8c7-460b60e5fa93
please try:
sudo runuser -u _gvm – gvmd --modify-scanner 78eceaec-3385-11ea-b237-28d24461215b --value dabd2710-aebd-4048-a8c7-460b60e5fa93
(I used a slightly different command, for docker…, but the concept should be that one above)