You have to recheck the fluid (cold) after the track. You will likely need to add Pentosin CHF11 from time to time. If you've been to the track and couple of times and never added any then that could have contributed to the failure.
Apparently, CHF11 evaporates quickly as well.
2015 F34 328iX GT Glacier Silver
2011 E90 M3 Monte Carlo Blue
2004 E46 M3 Imola Red