1050 intensity minutes show up for some rides but not others on 12.18, anyone having similar issues?

Two rides on Zwift in three days with same equipment/sensors etc, first ride recorded intensity minutes correctly but second ride did not even have the intensity field in GARMIN ride stats. I have also noticed this previously where it seemed to be intermittent at recording and I’ve only had this issue with the 1050 which is set as my primary training device. Any advice/suggestions would be appreciated. Thanks