Python 3 dependencies missing problem

I’ve been trying to upgrade my test/dev system, initially from 1.63 to 1.67 and now to 1.68, but seem to be going round in circles with the Python 3 dependencies.

I’ve upgraded PHP first to 7.3 and now to 7.4, and Python is sitting at 3.6.9:

Component | Version
--------- | -------
LibreNMS  | 1.67-84-g536bb8ac3
DB Schema | 2020_09_22_172321_add_alert_log_index (174)
PHP       | 7.4.10
Python    | 3.6.9
MySQL     | 10.1.44-MariaDB-0ubuntu0.18.04.1
RRDTool   | 1.7.0
SNMP      | NET-SNMP 5.7.3

I’ve also run pip3 install --user -r /opt/librenms/requirements.txt successfully:

Requirement already satisfied: PyMySQL in ./.local/lib/python3.6/site-packages (from -r /opt/librenms/requirements.txt (line 1))
Requirement already satisfied: python-dotenv in ./.local/lib/python3.6/site-packages (from -r /opt/librenms/requirements.txt (line 2))
Requirement already satisfied: redis>=3.0 in ./.local/lib/python3.6/site-packages (from -r /opt/librenms/requirements.txt (line 3))
Requirement already satisfied: setuptools in ./.local/lib/python3.6/site-packages (from -r /opt/librenms/requirements.txt (line 4))

However each time I run /opt/librenms/ it throws a Python 3 dependencies missing error:

Python 3 dependencies missing, switched to php71-python2 branch. FAIL

Can anyone point me at a glaring error I’m missing? Running on Ubuntu 18.04.4 LTS