I’m not saying it is solved, but if you were using an old version (and some 1.4 versions are very old) it wouldn’t be worth looking for a bug, which may have been fixed in 1.4.23.
hmmm, let me check the code with version 1.6. 
Hi,
We have similar problem with 1.6.
After the call is connected between the 2 end points and one of them send re-invite, asterisk don’t send it to other remote side.
Thanks
Erez