The Nigeria striker had been staying away from preseason training for the past fortnight after making a public transfer demand.
However, Lookman has since returned to Zingonia, at the Bergamo team's training centre.
Lookman had been spending time in Portugal and then at his home in London, awaiting an offer from Inter Milan, which, however, never actually arrived, at least not in the terms demanded by Atalanta.
Inter appear to have now closed their summer business, so leaving Lookman with the decision to return to Atalanta and begin training under coach Ivan Juric.
TMW says La Dea management are now weighing up how to punish the striker for his previous actions, though there is an appreciation by Lookman for his gesture this week.