Long AWU3 workout delayed, new workouts failed to start

Yesterday I ran a hard 50k (8hrs tracking time) and recorded the effort with my AWU3. When I finished the run, I paused as I crossed the finish line, then a few minutes later ended the workout. I got the perceived effort screen and changed "hard" to "all out" and clicked the crown. A few minutes later, sitting in my car, I went to check the total elevation gain for the run and saw the "no activity recorded" message in Fitness. My step count showed 33 miles, and my Rings showed a big effort. I restarted the watch and my phone . I tried starting another workout and got a "workout failed to start" warning. After driving home, and a couple more restarts, the activity suddenly appeared. This was aprox 3hrs after I finished the run. Obviously, this is suboptimal, though I am very glad it finally showed up.

Three other pieces of info:

1. Toward the end of the run yesterday (maybe the last hour) Siri stopped working. I tried texting my wife a couple of times and Siri did not start via voice command or the crown.
2. This was the third 50k I've tracked with this watch after switching to it from a Garmin device. The first one I had no issues with other than some sizable dropped HR due to the cold. So the next time, I used my new airpods to get the HR sensing to supplement the wrist hr. In the last couple hours of that run, the headphones started acting flaky (low volume) and I lost HR tracking again. I figured this was because my ears were also cold. So on the run yesterday I was using a chest strap heartrate monitor (bluetooth).
3. When the run finally showed up, the "all out" perceived effort I'd picked was gone, replaced by the "hard" it had originally suggested.

I'd love some input as to what anyone thinks is happening. I have a suspicion the issue might be the extra data being crunched from the external HR monitors.