Fitbit Charge 6 giving very inconsistent numbers for cardio load

[SquirrelRun]

Today I lifted weights for 33 minutes within an average heart rate of 120 bpm and Fitbit said the cardio load for that workout was 35, which seems reasonable. I then worked out on a stair stepper for 45 minutes with an average heart rate of 131 bpm and Fitbit said the cardio load for that workout was only 8. That seems far too low. My Fitbit Charge 6 accurately measured my heart rate and the durations of both workouts, but gave me a much lower number for cardio load for the longer and more intense workout. This is not the first time it's done something like that. I've also gotten cardio loads of zero for reasonably long and intense workouts. Again, the heart rate monitor was working fine during these workouts, so that's not the issue. Is there some way to fix this?

Moderator Edit: Formatting.

[RiekoC]

Hello @SquirrelRun 

Have you had a chance to update your Fitbit app to version 4.34? According to a Moderator post, version 4.34 included fixes to general Cardio Load and Cardio Target Load issues.

If you've updated to version 4.34 and have the inconsistency issues, please post in this thread (<-- click link) and tag DavidFitbit, the Moderator, in your post. Provide the details of the issue you're seeing, along with your Fitbit version #, if you're an Android or iOS user, & the phone/tablet you're using for the Fitbit app. He will forward your information to the engineering team so they know what issues were not fixed by the app update.

[SquirrelRun]

I'm having the exact same problem. I lifted weights for an hour and the cardio load was in the low 50s, which seems reasonable as my heart rate wasn't that high. I then worked out on a stair stepper for 25 minutes at a higher heart rate and the cardio load said only about 5. In the past, the cardio load has been in the mid 30s for a similar workout on the stair stepper. My fitbit did accurately register my heart rate and the duration of both workouts. So, the numbers I'm getting for cardio load are VERY inconsistent. I checked, and I do have the latest firmware: 210.26