Generally no. Time spent working in the United States is not counted toward the required year of employment abroad, though it does not necessarily interrupt continuity. An earlier continuous year within the three-year window can still satisfy the rule.
Count the year by geography, not by payroll
Hypothetical example: a Quispamsis managed-services company transferred its delivery director to the U.S. office informally for eight months while it arranged a lease, keeping her on Canadian payroll. The company assumes those months count because she remained a Canadian employee.
The L-1 rule looks at employment abroad, and periods of work in the United States are excluded from the calculation. The saving fact here is that the three-year look-back window is measured from the petition date, so if she worked continuously in New Brunswick for the two years before the U.S. stint, a qualifying year exists inside the window.
The company should document that earlier year precisely and explain the U.S. months openly, including the basis on which she was present. Pretending the months were spent in Canada would invite a finding of misrepresentation that no L-1A approval is worth.