To make sure I understood how GM is handling datums, I loaded a csv file of lat/lon points and set WGS84 as datum.
Then I loaded the same set but as OSBG36. There is then the expected separation owing to the different datums.
But then I loaded the same set a third time but as ETRS89. I was surprised to see the points are identical to WGS84.
As I understand it, WGS84 is moving apart from ETRS89 at about 2.5cm/year so I expected about 60cm separation or more.
Have I missed something here?