I got you a codepen ready to reproduce the issue:
Unfortunately my server is internal, so you'll have to change some url and template to have it working.
It works with a branch versionned feature point layer.
The workflow is the following:
Load the map and the branch versionned feature layer
Collect guids regarding edited and default versions for the feature layer. Generate guid for the session.
Then all requests are done through a direct fetch against REST API:
StartReading, StartEditing, ApplyEdits
ApplyEdits will return an editMoment
This editMoment is applied to FeatureLayer.historicMoment property to update the display.
At 4.19, you can create a point, you'll see it. The second point, you will not see it: historicMoment is not accounted for by the feature layer.
At 4.16, the sample works as expected.
It looks like at FeatureLayer.historicMoment does not allow a second mutation of historicMoment property.