Miller jumped from 11th on the grid to sixth in the opening corners before reaching the control line in eighth position at the end of the standing lap.
The Queenslander remounted and completed all 21 laps in the end, but was the last classified finisher in 21st position.
“Not how I wanted to start the season but those are the cards we were dealt today,” he said.
“The guys went a bit deep into Turn 1 and I tried to hold a tighter line and the front went away.
“I picked the bike up and was pushing afterwards but I was missing something today. I could not run close to the pace we needed. A head scratcher.
“We will try to work out what went wrong and try to fix it for Portimao.”
Miller leaves Round 1 of the season as one of seven riders who failed to score points at Lusail.
His Sprint performance was a somewhat similar story, also gaining five positions off the start only to plummet to 10th position by the end of Lap 2.
‘Thriller’ would finish 10th that Saturday evening, after which he stated, “We have an issue to sort and understand why we were passed a few times.”
That issue was reportedly electronics, specifically an issue with the anti-wheelie function.
It was a far better weekend for Red Bull KTM Racing team-mate Brad Binder, who finished second in both the Sprint and the Race, leaving him second in the championship at two points behind Francesco Bagnaia.
KTM Team Manager Francesco Guidotti described it as, “A great race by Brad. He was outstanding out there.
“This isn’t one of our best tracks – or hasn’t been – so to be second twice gives us a lot of confidence for the future.
“Also, the change we made to the bike after the Sprint made him happy.
“Crashing out meant that Jack could not take anything from the race but I am sure that he will be back near the front really soon.
“Portugal is another round for us and another challenge but with Brad in this kind of form and Jack with potential we can be optimistic.”
The Portuguese Grand Prix takes place at Portimao on March 22-24.