Different lawyers have different opinion on this issue. See the Q&A here:
Q: I was a H-1B holder, and used my Advance Parole to reenter the U.S. Do I lose my H-1B status and become I-485 pending?
A: If you resume your employment with the same employer for whom you had previously been authorized to work as an H-1 nonimmigrant without using your EAD, you can still keep your H-1B work authorization. Furthermore you can still apply for an extension of H-1B status. However, if after being paroled in, you change employers or work for your current employer with your EAD, you no longer have a valid H-1B nonimmigrant status, even though you can still lawfully stay in the U.S. during the I-485 pending period.
It is from http://www.hooyou.net/advanceparole/faq.html.
I heard that the above opinion is based on a USCIS memo, although I don't know where to find it.
PAforGC
Q: I was a H-1B holder, and used my Advance Parole to reenter the U.S. Do I lose my H-1B status and become I-485 pending?
A: If you resume your employment with the same employer for whom you had previously been authorized to work as an H-1 nonimmigrant without using your EAD, you can still keep your H-1B work authorization. Furthermore you can still apply for an extension of H-1B status. However, if after being paroled in, you change employers or work for your current employer with your EAD, you no longer have a valid H-1B nonimmigrant status, even though you can still lawfully stay in the U.S. during the I-485 pending period.
It is from http://www.hooyou.net/advanceparole/faq.html.
I heard that the above opinion is based on a USCIS memo, although I don't know where to find it.
PAforGC
RHTK said:Acc to big shot lawyer from Manhattan, I should not use AP to re-enter US if I want to maintain my H1b status. Acc to her, if immigration clerk at POE does not agree with Lamonte, he/she has a technical point and no lawyer would be able to defend the case. However, they say - - ignorance is bliss and most of immigration officials donot read these posts -!!
RHTK