Steps to reproduce
- Run GeoPackage through 1.2 executable test suite to confirm it is valid
- Load GeoPackage into QGIS to confirm that it works when loaded directly from a file
- Add new store, GeoPackage (mosaic)
- Name it, identify a file on file system
- When prompted, publish its "imagery" layer
- Layer Preview, pick layer, choose JPG
- Alternatively, load layer into QGIS as a WMS or WMTS layer
- Layer preview shows something resembling the layer
- Layer can be loaded into QGIS properly
- Layer preview shows up blank/white
- When loaded into QGIS, it shows up blank/white
As far as I can tell, the issue is because this tiles layer has global extents but is sparsely populated (with the bounding box identified in gpkg_contents). This test file has six tiles in it (to make it minimally reproducible). Note that cat tiles were used to avoid copyright issues.
GeoPackages with non-global extents (e.g., https://portal.opengeospatial.org/files/?artifact_id=74983) do work as expected.