Initial batch of bikes were incorrectly configured–reports are that the 790 Duke fuel tank settings were used, confusing the fuel gauge. All of those should have been fixed by a dealer reflash, most of 2019 and all 2020+ bikes should not be affected.
See the other fuel gauge article for details on how it works.
This failure mode is easy to spot. If the instrument panel indicates an empty fuel tank but the range indicator indicates many miles/kilometers available as the picture below shows then your bike is affected.
In the US (where they use weird unit of measure) it is possible for the dealer to switch the bikes to miles but for them to forget to switch the fuel cons to mpg. Those are controlled by two separate settings in the menu. Easy to fix, but may be confusing.
The bash plate is not installed at the factory, it is a dealer job to put it on when uncrating the bike. At least one dealer installed it incorrectly, not installing a bracket (#5 below). While you’re at it check that the canister vent is correctly clipped.
A few of reports (one by Andy Thomas on the Facebook group KTM 790 Adventure, another here) of liquid leaking from the standard exhaust staining everything. Probably condensation water. But the leak is not normal there, the exhaust should be sealed. Trip to the dealer for a fix.
Early bikes had a white residue deposit in the fuel tank. Probably some wax leftover from manufacturing. Extreme cases can block the fuel filter. Wax floats, if you fill your fuel tank and see white flakes at the surface get the bike to the dealer for a cleanup and filter change under warranty.
Apparently this is affecting only known serial number and KTM is asking dealers with the affected bikes to remove the tank and clean it, with a picture send to KTM to prove they did it. No customer should experience this at this point.