Comment 5 for bug 1772859

Since the ticket was opened against 18.04, and since 18.04 installations come with and use netplan by default with again networkd as the default renderer (and not NetworkManager), NetworkManager just cannot work by default.

If you want to work with NetworkManager on an 18.04 installation that's using netplan, the described re-configuration is needed and the renderer needs to be changed from networkd to NetworkManager - that's not a bug, that's intended and caused by the introduction of netplan (since about 17.10).
With that change NetworkManager should be able to manage qdio devices (see end of comment #3 - devices are listed as managed).

If you still have problems managing the devices _after_ doing the re-config there might be a bug, but I don't see that right now (but I for sure didn't covered your entire use case that I just don't know).

We understand that behavior is now a bit different compared to other distributions.

There were some bugs in the past on NetworkManager and netplan on previous Ubuntu releases, like the one mentioned by you in the bug description:
https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/1638842
which is a duplicate of:
https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/1676547
and already 'Fix Release' (since quite some time).
And btw. comment 26: https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/1676547/comments/26 confirms that the above renderer change works.

If issues still occur on other Ubuntu releases (not 18.04, but for example 16.04) that are not yet addressed in an LP bug, please open a separate bug on them.
And if there are still issues managing qdio devices after the change above, we may address them is a separate ticket, too.