Audio out of sync after saving

[Tdr]

I've edited one of my video (via Avidemux 2.8.1) and saved it.
I use VLC media player to watch/playback my videos, but this one video, the audio is out of sync when I play it via VLC,
but when I play it with Avidemux the audio is in sync. so I can't use the Shift function, to try to match the video and audio seeing that they are in sync.   

this happened once before and I think I saved the video when I got the "The beginning frame is not a key frame".
  I think this video also had the error but I'm not sure.
 
any Idea how or why this happened? (note: I still have the unedited version can try editing it with any suggestion I get)

Thanks

[eumagga0x2a]

1. If you use copy mode, never ignore warnings regarding keyframes.

2. Always use as current build of Avidemux as possible. The last release 2.8.1 is ancient, please try the last available 2.8.2 nightly.

If problem persists despite 1 and 2 taken into consideration, we'll have to investigate further.