I believe the investment in Medmen by Tilray is apx 3 years old. Any losses incurred by Tilray as a result would have long been accounted for.
Medmen is currently halted and appears to be going through heavy restructuring. Not much in terms of info available in terms as to if and when it will resume trading but I do wish the best to their team and all those holding shares of Medmen.
If you want exact dates as to when Tilray got involved with Medmen then you can visit the Tilray Homepage and review their Press Release section