Yes - if you have an H1B amendment application while you are employed in US - then you have to be in US while they file for your amendment. For my case - I will termed as a new hire as I resigned when I moved to CA and now joining back.
Once your application is filed and is in processing with USCIS - you can travel outside if you have a valid stamped visa to come back in (this was always termed risky by my attorney though).
Exactly. One more person who was having similar kind of amendment or extension was doing the same like you. Its different for people who are on Canadian entity of the employer and US entity. Hence wanted to clarify on it. Thanks for the info.