Time physically working in the United States for the Canadian employer does not count toward the required year abroad, though brief business trips are not fatal. Four months on site may mean the qualifying year must be found elsewhere in the three-year window, so map the dates before filing.
Map the qualifying year against the travel record
The rule requires one continuous year of qualifying employment outside the United States within the three years immediately preceding the petition. Periods spent in the United States working for the same employer, or in the United States in another status, are not counted toward the year but also do not break the three-year window. Take the director's travel history and pay records and mark every US stay.
If a clean twelve-month block exists in the window, use it and say so in the petition. If the four-month secondment falls in the middle of the only candidate period, options include waiting until a fresh twelve months accumulate in Canada or documenting that the secondment was intermittent business travel rather than a US placement. Do not file on an assumption that the examiner will not count the days; a request for evidence on this point delays the transfer by months, which is longer than simply waiting out a gap.