Are you judging diameter by the contour or DPM report? If it's the latter it shouldn't, for the former check the definition used in the solver.
To get DPM data during the run use the DPM Reports and .out files. I tend to prefer to set some number of injections each with a single diameter when trying to see what sizes go where. If the particles aren't coupled with the flow it's quick and very clear what's going on.
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