The William Haggas-trained mare hit the front inside the final furlong of the Queen Anne Stakes only to be collared late on by Lord Glitters and Beat The Bank.
She will now revert to taking on her own sex next month.
Runner-up in the race last year, the grey LORD GLITTERS powers home under Daniel Tudhope to land the (Group 1) Queen Anne Stakes at #RoyalAscot for @omeararacing!— Timeform Live (@TimeformLive) June 18, 2019
"Whether she went too early, which I think is harsh, or whether she just didn't quite get home I don't know," said Haggas of the mare, who won the Prix de la Foret last season.
"She's a pretty decent filly and I suspect we'll go for the Falmouth.
"She's in everything, she's in the Lennox. The problem is she's clobbered with a Group One penalty at the moment.
"The only Group One race over seven furlongs is the Foret, so we're stuck between going over a mile or six furlongs, and I think she's better over a mile than six.
"I don't want to go to America, I've done that with her, and the only Group One over seven in Europe is the Foret.
"I suspect she'll go for the Falmouth and then the Lennox or the Hungerford (at Newbury), I suspect."
Haggas has several smart fillies and mares in his care, with Move Swiftly now near the top of the tree after her win in the Duke of Cambridge Stakes last week.
Her owner Sheikh Rashid Dalmook Al Maktoum also has Pretty Baby, unplaced in the same Ascot race, and Beshaayir, a Group Two winner at the Curragh.
"Move Swiftly is not in the Falmouth because the owner has another filly, Beshaayir, who will go for the Falmouth after winning a Group Two in Ireland," said Haggas
"Move Swiftly could go for the Prix Rothschild at the end of July, there's no point going backwards with her.
"The owner, Sheikh Rashid, has three very useful fillies with Pretty Baby as well, but unfortunately they all want similar trips so we've got to try to keep them apart.
"On that ground I thought it was possible Move Swiftly could win first time up. She should have won at Lingfield in November, but she was drawn out wide and then she'd have gone for the All-Weather Final, but it just didn't happen."