I have a *.gdb which I normaly could load in QGIS version (3.4 / 3.8) following that instructions (or symply drag'n'dop): Installing File Geodatabase (*.gdb) support in QGIS?
But it returns a error: Invalid Data Source: [...] is not a valid or recognized data source.
I also tryed ogr2ogr to translate it first in to shapefiles:
ogr2ogr -f "ESRI Shapefile" ./shp ./Schoeningstedt.gdb
With no result. Whats wrong? Could anyone test my gdb? You can download it here: www.map-site.de/tmp/Schoeningstedt.gdb.zip