Training Effect, anaerobic benefit

I have 18 minutes workout in 4 and 5 HR zones https://connect.garmin.com/modern/activity/12114825047
But training effect shows that there is aerobic benefit, and no anaerobic.
I also have another workout, HR was primarily in 3 zone https://connect.garmin.com/modern/activity/12122382443
And it shows both aerobic and anaerobic benefits.  
Is it correct?