Hi, i had the similar case. My h1b amendment was in progress, and the orginial one was valid. I had already started working on the amended location too so my salary slips were containing the new location information.
My spouse attended the h4 visa stamping interview in mumbai consulate and presented the copy of my approved h1 and receipt of my amendment petition.
Visa officer stamped his passport with the validity end date of my approved petition without any issues.
So this is my success story, things can go either way, but fortunately they went the positive side for me.