Audio is out of sync with video

Hello everyone!
Got a few questions if you please.
The situation is this:
I record audio from concert hall. 48kHz, 24 bit. Frame rate of the project is 25. Three tracks. XY stereo and one additional mic. The signals are analogue and are splited in two ways: to FOH and to my console.
Video engineer records video and audio (audio comes from FOH - via AES, just the hall mix). Frame rate 25. ProRes HQ. Also he records his own mics for applause (two shotguns).
After the recordings are done video guy gives me two applause tracks I add them to mine and mix in Cubase. Then master two hours track in Wavelab and send it to video engineer back. He puts it in his project and… here appears to be a problem. My track is somehow out of sync with video.
What do you think of this? How is this possible? That’s because we don’t have a common timecode signal? What did I miss?

Thank you!