Compiled Script Using Multiprocessing Crashes When Run - python-3.x

Question

I wrote a simple script using Multiprocessing to fetch corresponding records from multiple databases, each containing different info for the same record. The script runs fine on my IDE and cmd, but whenever I tried to compile it with PyInstaller I got instant black screen followed by the sound of tons of error messages.
This is based on Python36, involving psycopg2, fiona and shapely as the files generated are shapefiles. But I compiled other scripts involving these modules before and they work fine.
import psycopg2
import fiona
from shapely.geometry import mapping
from shapely.wkt import loads
import re
import numpy
from multiprocessing import Process
def A(list):
for file in list:
query database A, generate shapefile for product A
def B(list):
for file in list:
query database B, generate shapefile for product B
def C(list):
for file in list:
query database C, generate shapefile for product C
if __name__ == '__main__':
e = Process(target=A, args=(scopes,))
m = Process(target=B, args=(scopes,))
p = Process(target=C, args=(scopes,))
e.start()
m.start()
p.start()
e.join()
print("\nProduct A is done")
m.join()
print("Product B is done")
p.join()
print("Product C is done")
The spec generated during the compiling are like this:
# -*- mode: python -*-
block_cipher = None
a = Analysis(['Scope Process Monitor.py'],
pathex=['C:\\Python36-32\\Lib\\site-packages\\osgeo', 'C:\\Users\\myname\\OneDrive - Company\\Scripts\\Scope Process Monitor'],
binaries=[],
datas=[],
hiddenimports=[],
hookspath=[],
runtime_hooks=[],
excludes=[],
win_no_prefer_redirects=False,
win_private_assemblies=False,
cipher=block_cipher,
noarchive=False)
pyz = PYZ(a.pure, a.zipped_data,
cipher=block_cipher)
exe = EXE(pyz,
a.scripts,
a.binaries,
a.zipfiles,
a.datas,
[],
name='Scope Process Monitor',
debug=False,
bootloader_ignore_signals=False,
strip=False,
upx=True,
runtime_tmpdir=None,
console=True )
I am guessing I need to limit the use of CPU in the script somewhere, but this is actually my first time trying Multiprocessing module, so I do not know how.