Hi Martijn
I believe the trick is here to bring the solo flute in front of the orchestra - as max mentioned as well above.
I don't know how you mixed the orchestra. If you used MIR then try to route the signal of the flute not through MIR.
Just use VSLs HyperReverb for example within the flute channel. Choose a concert hall preset and switch off the ERs (early reflections) so that you only get some "tail" but no depth.
This will work with other algo-reverbs as well of course.
For simulating a front sound you also could insert an exiter into the flute channel.
Enhance the highest (shiny) frequences a bit (which is the case with closer instruments). Max mentioned this as well.
then balance the volume between the orchestra and the flute so that the flute always sounds "over" the accompaniment.
This could be a job for the "trackoutomation" within your DAW.
Even if you didn't use MIR then route the Flute through a separate "depth-system" (reverb).
All the best
Beat