Fenix 5 Plus does not load maps properly with 19.10 and TopoActive 2022.10

I have a Fenix 5+, upgraded to 19.10, and maps TopoActive Europe 2022.10

The watch does not display correctly the maps during the activity : it's slow, parts are blank, or it's even full blank. And it's draining the battery faster than before.

Everything was working fine with previous firmware and previous map.

What I tried:

- reinstall the maps on a new computer (to force a new download) : no change

- reduce the map details in the activity  setup : slightly better, but still lot of blank displays when running in a city (in Paris for example)

- remove the map "contour" in the activity setup : same as above, still super slow to display the map and partial display

  • I hit this (again!) after upgrading to 19.30.  I think this is either the 3rd or 4th time I've hit this after upgrades (I know it's at least 3, as this is the third post I've done about it here!).

    Standard symptoms - watch was slow to reboot.  Maps were very slow to come up.  Routing operations (either 'back to start' or to a point sent via Explore) hung for minutes in 'calculating route' before I finally gave up and cancelled.

    Reinstalling the maps didn't help (although it did on at least one occasion in the past). I ended up going in and deleting all of the img and related files from the watch, then reinstalling the maps via Garmin Express which did fix the problem.

    I'm not sure if this is related to the upgrade process as such, or if the maps are already corrupted and installing a new version triggers a rescan of them or something - but in this case I rebooted the watch before the upgrade and it didn't have the problem, then on the post-install reboot it did, so it's the upgrade that is triggering the issue in some way or another.