I think I may have a good idea why no intensity minutes were recorded for my workout yesterday but worth noting for others if it helps.
So I generally record my strength workouts as a just a timed cardio workout and then just swap the activity type in the app on my phone after. my identical workouts in previous weeks have been recorded perfectly, just yesterday 26th Feb was not added to the intensity minutes.
What I think has happened is the following: I had signed up for the App Beta prior. I begin my watch and my workout and check in the app half way through realise i dont like the beta very much and remove myself from the beta, this is all while the watch is currently in the process of activly recording the activity. I finish the workout and no intensity minutes have been added. I am presuming something to do with me swapping out of the Beta mid workout session has caused a conflict or loss of data.
I have a spin class coming up tonight and will see if that records as usual.