Double blow for Florence
The Olympic silver medallist and reigning World Cup champion went quickest in the C1 Canadian heats but then picked up 52 seconds of penalties in the semis to plummet from eighth to 28th with only the top ten going through.
The Forth Canoe Club star also failed to reach the C2 final with Rich Hounslow after four more penalties left them back in 12th place.
"It's disappointing," admitted Florence. "But I'm looking ahead now to the next World Cup in Spain (next weekend]."
Aberdeen's Tim Baillie and Etienne Stott did make the C2 final but could finish only ninth.