Time spent working in the United States is generally not counted toward the one continuous year of qualifying employment abroad, although in the usual case it does not simply erase eligibility either, because the three-year lookback window is affected.
Count the months abroad, then check the window
The rule asks for a year of employment with the organization abroad within the three years before the petition. A person who spent part of that period working in the United States has fewer qualifying months inside the ordinary window, and the analysis then turns on how the window itself is treated in their circumstances. This is precisely the sort of question that should be resolved by someone qualified, on the documents, rather than by the employer's own reading, because the consequences of getting it wrong are a denial rather than a request for more information. What the company can do usefully is produce the raw material: a month-by-month record of where the employee was, who paid them, and under what contract, supported by payroll and travel evidence.
Hypothetical example: Nadia has been regional director for a Canadian renewable-energy equipment distributor and is proposed to lead its U.S. affiliate. A first review should produce a three-year employment calendar, an ownership diagram, and a before-and-after organization chart. Payroll and travel records settle the qualifying foreign employment; corporate registers settle the relationship; job descriptions and reporting lines settle managerial capacity. She should test those points before announcing a transfer date. A title alone is not enough, and a role dominated by selling, installing, or routine delivery can undermine an otherwise strong corporate case.