Remote Connection fails in setup of Python data-science client for SQL Server Machine Learning Services

Question

I am trying to test the remote connection of a Python data-science client with SQL Server Machine Learning Services following this guide: https://docs.microsoft.com/en-us/sql/machine-learning/python/setup-python-client-tools-sql (section 6). Running the following script

def send_this_func_to_sql():
    from revoscalepy import RxSqlServerData, rx_import
    from pandas.tools.plotting import scatter_matrix
    import matplotlib.pyplot as plt
    import io
    
    # remember the scope of the variables in this func are within our SQL Server Python Runtime
    connection_string = "Driver=SQL Server;Server=localhost;Database=testmlsiris;Trusted_Connection=Yes;"
    
    # specify a query and load into pandas dataframe df
    sql_query = RxSqlServerData(connection_string=connection_string, sql_query = "select * from iris_data")
    df = rx_import(sql_query)
    
    scatter_matrix(df)
    
    # return bytestream of image created by scatter_matrix
    buf = io.BytesIO()
    plt.savefig(buf, format="png")
    buf.seek(0)
    
    return buf.getvalue()

new_db_name = "testmlsiris"
connection_string = "driver={sql server};server=servername;database=%s;trusted_connection=yes;" 

from revoscalepy import RxInSqlServer, rx_exec

# create a remote compute context with connection to SQL Server
sql_compute_context = RxInSqlServer(connection_string=connection_string%new_db_name)

# use rx_exec to send the function execution to SQL Server
image = rx_exec(send_this_func_to_sql, compute_context=sql_compute_context)[0]

yields the following error message returned by rx_exec (stored in the image variable)

connection_string: "driver={sql server};server=servername;database=testmlsiris;trusted_connection=yes;"
num_tasks: 1
execution_timeout_seconds: 0
wait: True
console_output: False
auto_cleanup: True
packages_to_load: []
description: "sqlserver"
version: "1.0"
XXX lineno: 4, opcode: 0
Traceback (most recent call last):
  File "<string>", line 3, in <module>
  File "E:\SQL\MSSQL15.INSTANCE02\PYTHON_SERVICES\lib\site-packages\revoscalepy\computecontext\RxInSqlServer.py", line 664, in rx_sql_satellite_pool_call
    exec(inputfile.read())
  File "<string>", line 34, in <module>
  File "E:\SQL\MSSQL15.INSTANCE02\PYTHON_SERVICES\lib\site-packages\revoscalepy\computecontext\RxInSqlServer.py", line 886, in rx_remote_call
    results = rx_resumeexecution(state_file = inputfile, patched_server_name=args["hostname"])
  File "E:\SQL\MSSQL15.INSTANCE02\PYTHON_SERVICES\lib\site-packages\revoscalepy\computecontext\RxInSqlServer.py", line 135, in rx_resumeexecution
    return _state["function"](**_state["args"])
  File "C:\Users\username\sendtosql.py", line 2, in send_this_func_to_sql
SystemError: unknown opcode
====== servername ( process 0 ) has started run at 2022-06-29 10:07:11 W. Europe Daylight Time ======
{'local_state': {}, 'function': <function send_this_func_to_sql at 0x000001982BC0F1E0>, 'args': {}}

What is going wrong here? Line 2 in the script is just an import (which works when testing Python scripts on SQL Server directly). Any help is appreciated - thanks.