Since the latest github commits, it seems, there is something broken. Workaround:
By selecting a few words and trying to insert a hyperlink with the symbol bar icon, I’ve got a problem: The link I’ve copied before will overwrite the selected text, insted of filling the text field of the hyperlink prompt.
If I wrote more than just a few words and overwrite them, they will be lost for ever! I can’t undo this to restore my text.