Training Load & Training Status are incorrect

yes, here another with the same behaviour, totally inaccurate

Please be aware that those values are calculated from data like pace, distance, heartrate, weight etc.
The rest is estimation. The watch cannot know if you run on a flat road or in deep mud, snow, rough terrain, small waves below detection limit of the altimeter, headwind etc...

The result is that Training load and VO2 max go down if you do several runs under heavy conditions because your heartrate is higher and/or your pace is lower. 

If any of your data is wrong, e.g. heartrate, which happens more often with optical HRM but also sometimes with a strap, your status will definitely be affected.

Overall the Fenix is a measuring device and like all measuring devices if can only measure a sum of errors!

I get that, but the error is quite material when you ran a half-marathon and the watch still states you have been recovering for the past couple of days. And status did not change after training the following day and intense interval workout after that. It seems quite strange, and, as you correctly point out, could be due to an issue with optical HRM. 

I have the same status and this was after a 16 mile run on Sunday 31st - actually my load in August was my heaviest running load ever but I too see a large drop in training load reported even though my mileage was up 22% on the previous month.

I run with a heart rate belt.

This may or may not be connected - but my 7 day load has been showing ridiculously low numbers even though I've been doing a lot of high intensity virtual cycling during the last week. I put it down to me having uploaded the workouts from .fit files provided by the virtual cycling platform I'm using (RGT) rather than from my Garmin, but I'd have thought the algorithms would still have given a reasonable estimation of load despite that - the files include HR, power, position and elevation after all. So maybe there is a back end problem, not related to the Garmin devices themselves.

What does the Performance widget on the watch show? The same or something else?

I don't use Connect so there is no back-end processing involved in my case, and the Performance widget shows a low training load which had me wonder as well, but I'm not ruling out that the activities in the past week were just not as intense as I perceived them to be. It has been much cooler, which makes my heart rate quite a bit lower.