Is it just me or does particle tracing flow across dry areas and continue in the wet areas. Have a river through a low area (ha see other recent posts by moi) with meandering sloughs and as the water rises the particles (static and moving) do follow the river and enter the low areas appropriately, but as the sloughs fill up the particle tracing will act as described. Looks good when completely flooded. This is more an observation than a question of how to fix.
Not sure if this is what you’re describing, but sounds like you have some leaking. Putting in breaklines on high ground can prevent this. But in general, yeah, particle tracing is a graphical representation of the computed flow directions. It doesn’t always work perfectly for every situation.