Based on your post --(1) while your visa H-1B exists, because you have left the USA for at least a year -- it is no longer valid -- thus for 2018 you would be Non-Resident Alien. (2) if you are permanent resident of Canada, living in Canada , working from home in Canada , your income ( even if paid by an US entity ) does not come under US taxation. Absent some income from US sources ( like rental property, business income, investment income, capital gains etc. ), there is no need for you to file a US return.
What am I missing here?
Namaste ji
