Exception: No elements in volume 33 47

[mdiazv64]

Hello,
I want to generate an STL mesh from a random distribution of ellipsoids in a .csv file.
The following exception occurs in the code below:
Exception: No elements in volume 33 47

Would you be so kind to check why this is happening since I have no idea?

from math import pi
import pygmsh
import meshio

from csv import reader

with open('data_1_ell.csv', 'r') as csv_file:
    csv_reader = reader(csv_file)
    # Passing the csv_reader object to list() to get a list of lists
    list_of_rows = list(csv_reader)
    #print(list_of_rows)

#for element in list_of_rows:
#    print(element[0], element[1], element[2], element[3], element[4], element[5], element[7], element[8] )
#print(type(list_of_rows))
#print(list_of_rows[1][0:3])


def ellipsoid_rotated(obj, center, angle1, axis1, angle2, axis2):
    geom.rotate(obj, center, angle1, axis1)
    geom.rotate(obj, center, angle2, axis2)

mesh_size_obj = 0.1
ind = 0
limit = 50
object_list=[]
with pygmsh.occ.Geometry() as geom:
    geom.characteristic_length_max = 0.1
    for element in list_of_rows:
        if (ind > 0 and ind < limit):
            obj = geom.add_ellipsoid([float(element[0]),float(element[1]),float(element[2])], [float(element[3]),float(element[4]),float(element[5])], mesh_size=mesh_size_obj)
            ellipsoid_rotated(obj, [float(element[0]),float(element[1]),float(element[2])], float(element[7]), [0.0, 0.1, 0.0], float(element[8]), [0.0, 0.0, 0.1])
            object_list.append(obj)
        ind = ind + 1
    print("Performing union of objects ...")
    geom.boolean_union(object_list)        
    print("Creating mesh ...")
    mesh = geom.generate_mesh()
print("Saving .stl file")      
mesh.write("ellipsoids_rotated_" + str(limit) + "s.stl")

data_1_ell.csv