Actually, I don’t have conda in my environment, only in my base environment. Could that affect the behaviour?
In my fastai environment:
(fastai) g:\Confirmation>conda list conda
# packages in environment at G:\Anaconda3\envs\fastai:
#
# Name                    Version                   Build  Channel
_anaconda_depends         2019.03                  py36_0
anaconda                  custom                   py36_1
anaconda-client           1.7.2                      py_0    conda-forge
anaconda-project          0.8.3                      py_0    conda-forge
msys2-conda-epoch         20160418                      1

In my base environment:
(base) C:\Users\User>conda list conda
# packages in environment at G:\Anaconda3:
#
# Name                    Version                   Build  Channel
conda                     4.7.12                   py36_0    conda-forge
conda-build               3.18.6                   py36_0    conda-forge
conda-package-handling    1.6.0            py36h2fa13f4_0    conda-forge
msys2-conda-epoch         20160418                      1
nb_conda                  2.2.1                    py36_0    conda-forge
nb_conda_kernels          2.2.2                    py36_0    conda-forge

How should I get conda into my fastai environment? I attempted conda install conda but it looks like it will mean a lot of extra processing to get working:
(fastai) g:\Confirmation>conda install conda
Collecting package metadata (current_repodata.json): done
Solving environment: \
The environment is inconsistent, please check the package plan carefully
The following packages are causing the inconsistency:

  - conda-forge/noarch::anaconda-client==1.7.2=py_0
  - defaults/win-64::anaconda==custom=py36_1
  - conda-forge/noarch::anaconda-project==0.8.3=py_0
  - conda-forge/win-64::bkcharts==0.2=py36_0
  - conda-forge/win-64::bokeh==1.4.0=py36_0
  - conda-forge/noarch::dask==2.7.0=py_0
  - conda-forge/noarch::dateparser==0.7.2=py_0
  - fastai/noarch::fastai==1.0.34=py_1
  - conda-forge/win-64::ipykernel==5.1.3=py36h5ca1d4c_0
  - conda-forge/noarch::ipywidgets==7.5.1=py_0
  - conda-forge/noarch::jupyter==1.0.0=py_2
  - conda-forge/noarch::jupyterlab==1.2.2=py_0
  - conda-forge/noarch::jupyterlab_server==1.0.6=py_0
  - conda-forge/win-64::jupyter_client==5.3.3=py36_1
  - conda-forge/noarch::jupyter_console==6.0.0=py_0
  - conda-forge/win-64::matplotlib==3.1.2=py36_0
  - conda-forge/win-64::matplotlib-base==3.1.2=py36h2981e6d_0
  - conda-forge/win-64::notebook==6.0.1=py36_0
  - conda-forge/win-64::pandas==0.25.3=py36he350917_0
  - conda-forge/noarch::qtconsole==4.5.5=py_0
  - conda-forge/win-64::scikit-image==0.16.2=py36he350917_0
  - conda-forge/noarch::seaborn==0.9.0=py_1
  - conda-forge/win-64::spyder==3.3.6=py36_1
  - conda-forge/win-64::spyder-kernels==0.5.2=py36_0
  - conda-forge/win-64::statsmodels==0.10.1=py36hfa6e2cd_1
  - conda-forge/win-64::widgetsnbextension==3.5.1=py36_0
  - defaults/win-64::_anaconda_depends==2019.03=py36_0
done

## Package Plan ##

  environment location: G:\Anaconda3\envs\fastai

  added / updated specs:
    - conda


The following NEW packages will be INSTALLED:

  conda              conda-forge/win-64::conda-4.7.12-py36_0
  conda-package-han~ conda-forge/win-64::conda-package-handling-1.6.0-py36h2fa13f4_0
  python-dateutil    conda-forge/noarch::python-dateutil-2.8.1-py_0


Proceed ([y]/n)?