I've tried to make some edits on the beta cluster and they appear to save without any errors. If using the VisualEditor it even shows the "Your edit was published" popup. But on refreshing the page it shows the unedited version, and my edits don't appear in the history, my contributions, or recent changes. There's no errors in the browser console when saving.

Reproduced on various beta sites (en.wikipedia, de.wikipedia, meta), using both source editor and VisualEditor, and both logged-in and logged-out.