Very few coaches use target minutes and I have very limited experience with it.   But I assumed that, if you set for maximum minutes, your players would keep playing until they fouled out.   Target minutes doesn't  have a setting for 'foul trouble only' , like  fatigue minutes.  Your player, Darlington, picked up 3 fouls in the first half and didn't start in the 2nd. You had the same thing happen to a guard in an earlier game.   So, it appears that the engine is set up that way. I'd send in a ticket.

On your player game plan, make sure you've  indicated 'more agressive' in the fouling category. 

My next thought was that your uptempo was tiring your players, forcing a substitution.  I thought, though, that the 'maximum minutes' would take precedence over fatigue and a tired player would keep playing. Since target minutes is so rarely used,  it's possible this is a problem that hasn't been noticed before.  Again, I’d send a ticket.