The 26-year-old blamed a slow start for missing out on a chase for the finish at the Herculis meeting as Ajee Wilson of the USA broker clear for victory.
But Muir, who will target a first global title in the 1500m in Doha in the autumn, extended her lead at the top of the UK rankings by clocking 1:58.42 to take third place in the non-Diamond League race.
And fellow Scot Lynsey Sharp was just behind in fourth, recording her fastest time for almost two years of 1:58.76, well inside the qualifying mark for the worlds.
“I need to go out harder over that first 200m,” Muir admitted. “I’m very happy with the personal best. It’s been a while since I have run one and it’s always going to be hard, going up against these girls. But I feel like I’m in a personal best shape for the 1500m I’ll run London next weekend.”
Jake Wightman’s first tilt at earning Diamond League points this summer saw him deliver a late sprint to snatch eighth place in the men’s 800m.
Sifan Hassan of the Netherlands broke the world record in the women’s mile, winning in 4:12.33.