Just to confirm that the most possible culprit is the DNS compression that behaves differently from what BIND is doing, and perhaps those devices expect the DNS packet to look exactly like this instead of following the DNS specification.
Unfortunately it looks like that even disabling DNS compression altogether doesn’t help some of the devices (Garmin namely), so even though Knot Resolver does follow existing standards, we will now implement the exactly same DNS compression algorithm to ensure compatibility with those horrible devices.
This needs to be fixed in libknot and therefore it will takes us some time to fix it properly, so please be patient (and use non-Omnia resolver for those devices).