Anaerobic effect is a joke

I think the "effect" features mainly used for running/cycling. To get Anaerobic effect score, the heart rate kind of needs to be in maximun zone, like 95-100%.

That doesn't make any sense. Weightlifting is by definition an anaerobig excercise.

The intervals are 20-60 seconds training, 60-120 seconds resting. Noon ever gets to 95-100% HR in half a minute of weight lifting.

I get what you mean. I would say these features are designed specifically for running and cycling.

I hope they did not omit the algorithms for anaerobic training effect for other sports than running and cycling. This was one main reason for upgrading from my Amazfit Stratos (similar to 235). If so, I would have to return it and go with Polar. 

Polar can not calculate anaerobic effect of weight training either. Anaerobic effect in weight training is local. But these watches gauges global anaerobic state of the body by hr data. So, they work for running, cycling or walking

0.0 is a bit of surprise there. Something might be off. I mean, I wouldn't expect a huge AnTE from that workout, but something should be there.

Might be time to contact support. 

Not that it affects that situation, but there is a bit of definition confusion at play in some of the other posts in this thread. 

Aerobic and Anaerobic both refer to the different ways your body produces ATP, the molecular fuel your muscles break down to contract. Just because your activity is weight lifting doesn't mean that the energy production is anaerobic or that your efforts were of a type that necessarily helped you develop anaerobic energy production capacity down the road. 

I've been lifting weights for 6 years and I suffer from exactly the same problem. I've been using the watch for 3 months and  lift weights 4 times a week. I haven't managed to get even a little anaerobic score so far. Training effect scores are only concerned to running and cycling to my understanding, it doesn't take account weight lifting workouts. It is funny because weight training is the most anaerobic exercise in fact.

I have one more complaint with firstbeat algorithm. It doesn't take into consideration weather temperature, humidity, incline rate and efforts made in previous activity that recently finished.

For instance, Mondays are my leg day. I practise leg only but heavily (both squat and leg press and much more) It doesn't give me any anaerobic points. Moreover, i save my leg activity and immediately after leg workout, i run on treadmill. As you may appreciate, due to making a lot of efforts for leg session, i become tired and my running performance doesn't become as same as while i'm rested. However, it doesn’t take into consideration my previous activity and shows tendency to decrease my VO2max score.

Yesterday I did some weight lifting and got TE aerob 2.7 and anareob 2.0. Max pulse was 150, avg. 128, duration 24min. I used cardio workout type because weight lifting required me to mark some sets.

I think it's because of you pick cardio as workout mode. Here is my data after 38 min of weight lifting exercise with 2.1 aerobic and 0.3 anaerobic effect. Average HR 116, Max. HR 150.