via Elliotte Friedman of Sportsnet,

As the NHL and NHLPA negotiate an agreement to resume play, work visas must be addressed. The league’s calendar "ends" on June 30, and visas expire at that time. Since the pandemic makes it extremely difficult for the quick process of renewals, players were told in a memo "it is essential that you return as soon as possible to give your club enough time to process a renewal application on your behalf."

The worry is that players who do not return over the next week will have difficulty entering North America in time for the potential opening of training camps on July 10.

There is going to be some dissatisfaction, because it is not mandatory for players to show up in their NHL cities until the start of those camps. Now, they are being asked to arrive 19 days earlier, with no certainty of resuming — although a ton of work is being done to prepare for it. Players were told to check with their teams about local quarantine rules. (There is a 14-day quarantine coming into Canada, although lobbying is underway to have team facilities included in the bubble.)