Question of tactics
The filly, which started the $3.50 equal favourite, finished runner-up to the other equal favourite Loose Unit in the Mitre 10 Mega Beenleigh Handicap (1660m).
Trained by Kelso Wood, Lassie Mactavish settled midfield for Jones before running home strongly to be beaten 2-3/4 lengths.
Wood said his instructions to Jones were to make sure Lassie Mactavish raced on the speed.
Stewards questioned the apprentice as to why he allowed the three-year-old to settle midfield before adjourning their inquiries to examine betting records from the race.
Originally based with Stephen Lee at Ballina before spending time at the Sydney stable of Anthony Cummings, Jones only recently moved to Brisbane in search of a fresh start.
The 17-year-old returned to riding in May after serving a three-month careless riding suspension over a race fall at Grafton in December in which jockey Daniel Baker was killed.
Jones made a successful start to his Brisbane venture, winning the final race on the Ipswich Cup program at Bundamba last Saturday aboard Tornadic Sky.