I'm a developer of Universal Media Server, which has supported FFmpeg since its first version but we're looking to use newer builds and add better support/features for FFmpeg.
The problem is that between the March 19th and March 25th releases of FFmpeg something changed to break seeking.
There are some things I can do to investigate it still but I just wanted to quickly ask if you changed anything in the build environment between those dates that would account for this change?
Cheers!