Training load not synced between two watches

I just discovered that Training load / status is a property of a single Garmin device only, but it is apparently not synced via multiple devices.

How did I notice? I recently got my F5+  replaced by Garmin (maps issues). After going for a (heavy: anaerobic 2.4, arobic 4.7) run with the new watch, I was surprised that the training load / status didn't change at all. This was due to the fact the new watch has it's own training status. Now I can switch between the two in the Garmin connect app.

I thought there was the Physio TrueUp feature that should avoid exactly this. It was activated on the new watch (before I went for the run), but apparently, this didn't help. I noticed that it was not activated on the old one though, but in principle, this should only affect the training load on the old watch (it is very stupid to me that there are training loads per watch anyway).

Does anyone know how I could get a proper training load/status?

Thanks!

Edit: I changed the title, was a bit too provocative (I was a bit upset, when I realised/wrote it, sorry).