Yeah.. So.. After some further inquiry here's a top tip for everyone running into the same problem:
don't trust the documentation:
exportRaster(path='', format=RasterFormatTiles, image_format=ImageFormatNone,
raster_transform=RasterTransformNone[, projection ][, region ], resolution=0,
resolution_x=0, resolution_y=0, block_width=10000, block_height=10000,
split_in_blocks=False, width=0, height=0[, world_transform ], nodata_value=-32767,
save_kml=False, save_world=False, save_scheme=False, save_alpha=True,
image_description=''[, image_compression ], network_links=True, global_profile=False,
min_zoom_level=-1, max_zoom_level=-1, white_background=True, clip_to_boundary=True,
title='Orthomosaic', description='Generated by Agisoft Metashape',
source_data=OrthomosaicData[, asset], north_up=True, tile_width=256, tile_height=256[,
progress])
Export DEM or orthomosaic to file.
global_profile (bool) – Use global profile (GeoPackage format only).
setting
global_profile = True fixed it and it becomes pretty obvious that this parameter does not just have an impact on the mentioned GeoPackage format... Maybe that should be in the documentation...
Cheers, this has prevented me from ever upgrading beyond 1.7.4..