Esse script de shell gerará suas miniaturas de tamanhos de 128px e 360px para que você veja pelo menos algo no visualizador.
sqlite3 ~/.local/share/shotwell/data/photo.db \
"select id||' '||filename from PhotoTable order by timestamp desc" |
while read id filename; do
for size in 128 360; do
tf=$(printf ~/.cache/shotwell/thumbs/thumbs${size}/thumb%016x.jpg $id);
test -e "$tf" || {
echo -n "Generating thumb for $filename ($tf)";
convert "$filename" -auto-orient -thumbnail ${size}x${size} $tf
echo
}
done
done