GRAPH API - GET all Group Members

Question

As a MS Teams Admin, I want to see all Teams and their Members, So that I can administer and report on the count of teams and their spread of members across my organisation.

I am using a Power BI dataflow (Power Query) to achieve this, by executing three different queries (in one dataflow) and joining the returned datasets in a single Power BI dataset.

I am experiencing an issue with one of the three queries; GET all Group Members:
https://github.com/pitchfol/GRAPH/blob/main/Power%20Query%20-%20GET%20all%20Group%20Members

This query refreshes the dataset successfully sometimes, and not every time is successful. Other queries work fine and I have tested my permissions and credentials for the App used and credentials in Power BI.

I'm keen to hear if anyone else has tried this with success or had issues when traversing the GRAPH v1.0/groups endpoint to return Members for each Group.