Olympic 400m hurdles finalist Eilidh Doyle finished second behind Olympic champion Dalilah Muhammad in Lausanne.
And high jumper Robbie Grabarz, fourth in Rio, was runner-up to Qatar's Mutaz Essa Barshim.
The meeting also saw Jamaican double Olympic sprint gold medallist Elaine Thompson back on the track.
The 100m and 200m gold medallist in Rio won the 100m with ease in a time of 10.78 seconds, while Britain's Desiree Henry was fourth in 11.17 seconds.
Long jumper Ugen might have beaten American Bartoletta with a leap of 6.71m but had to settle for the runner-up spot behind Serbia's Ivana Spanovic.
Team-mate Proctor was fourth (6.48m) - a place ahead of last week's gold medallist.
Doyle, meanwhile, leads the Diamond League 400m hurdle standings.
Djibouti's Ayanleh Souleiman set the fifth-fastest time ever to win the men's 1,000m in 2 minutes 13.49 seconds, with American Olympic 1500m champion Matthew Centrowitz sixth.
Two American bronze medallists from Rio won their events, with LaShawn Merritt posting 44.50 seconds in the 400m, and Sam Hendricks setting a pole vault meet record of 5.92m.
While world-record holder Kendra Harrison  - who failed to make the US squad for Rio - took the 110m hurdles in 12.42, a time that would have been good enough for gold in the Olympic stadium, as Britain's Cindy Ofili matched her fourth place in Rio.
Joel Fearon, the bobsledder who is Britain's fastest man this year but did not qualify for Rio, finished third in the men's 100m race in 10.05 seconds.
Compatriot Harry Aikines-Aryeetey was eighth (10.43) in a race won by Asafa Powell in 9.96 - the Jamaican's 97th legal sub 10-second time in the event.
Lynsey Sharp produced her third fastest time of the year (1:58.52) to finish third in the 800m.
The Diamond League series continues in Paris at the Stade de France on Saturday, 27 August.
Britain's Lorraine Ugen and Shara Proctor beat Olympic champion Tianna Bartoletta in the long jump in the first post-Rio Diamond League meeting.