Barcelona forward Ousmane Dembele was two hours late for a training session on Sunday, sources have told ESPN FC.
Dembele, 21, was tracked down at his home by club security staff a day after starring in the 4-0 derby win over Espanyol.
In October, sources told ESPN FC that Barca had concerns about Dembele's off-pitch behaviour.
The France forward then failed to report for a training session the following month, with coach Ernesto Valverde dropping him from the squad against Real Betis as a result.
Valverde, speaking at a news conference ahead of this week's Champions League match against Tottenham, tried to downplay Dembele's lateness, but sources said the club hope the player can address the situation quickly.
Barca also have concerns about the company Dembele keeps and feel his childhood friends could do more to ensure that he remains professional.
Urbano Ortega, who was assistant to former sporting director Robert Fernandez, said Barcelona had received reports about Dembele's off-pitch conduct when signing him from Borussia Dortmund last year.