Broadcast planning chief Mike North said the league still targets mid-May, but release could move from May 13 to May 20 or 21.
The holdup centres on an unassigned five-game package, with YouTube, Netflix and Fox cited as possible homes before the full schedule can be finalised.
The league is also preparing for a record nine international games, while teams such as Green Bay already know opponents but not dates, times, byes or prime-time slots.
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