1.11.6: GPS data not shown on map if only in xmp sidecar

[tstimg]

XnView: MP 1.11.6 - 64-bit
OS: Windows 10 - 64-bit / Linux Debian 13 - 64-bit

GPS coordinates only present in a xmp sidecar file are never displayed on the map.

Effect: No location marker on map.

To reproduce:
1. Use (read-only) image without embedded GPS coordinates
2. Add GPS coordinates using another program (eg. exiftool), writing only to xmp sidecar
3. Ensure that the new coordinates only appear in the xmp sidecar file (exif:GPSLongitude, etc...) and not embedded in the image file itself
4. Select image in XnView MP

Actual behaviour (bug): Map shows no location marker

Expected behaviour: Location marker should appear on the map even if the coordinates are only present in a xmp sidecar file.

The presence of GPS coordinates in the xmp sidecar file is acknowledged by the appropriate overlay icon in the 'Thumbnail View', they are listed in the 'Details View', the right-click 'Metadata > Open GPS location in' works as expected and the 'info' panel show a map tab (but either centred on "London" or with maker still showing the last known location). This behaviour does not change whether 'Metadata > Import > Exiftool' in settings is selected or not. Right-click 'Metadata > Edit GPS...' however shows only zeroes.

Sidenote: My understanding was that you should try to avoid writing anything directly into raw files, but right-click 'Metadata > Edit GPS...' does write the new coordinates directly into the raw file instead of into a xmp sidecar (tested with RAF and DNG files), regardless of the 'Metadata > Sidecar' settings.