Subclips were prepared in the Resolve 16 with a movie and embedded audio track. In 17 the subclip on the timeline is out of sync - but the main clip all is in sync. When i hit "edit subclip" all is out of sync", but when I click the button to allow for EXTANTS all becomes in sync. Dropping the in sync video/audio produces an out-of-sync clip on the timeline.
I have tried to create a new timeline - no success
I have deleted the cache - no success
I have restarted the system - no success
I have slightly moved the in and out point of the subclip to see if would "regenerate" - no success
It is worth mention that these particular clips have the audio and video on the same file - there is no way for them to go out of sync unless I select only one of the tracks and move it relative to the other - and then I'd see the red warning sign - but these have not been shifted and in fact are in perfect sync - just not playing that way
I welcome any ideas but likely am reporting a bug.
My workaround to fix this problem: 1. Make audio file from the main clip (I used audacity) 2. Import said audio file into you project 3. Select said audio file and all subclips 4. Right Click -> Auto Sync Audio -> Based on timecode
In case you have those subclips in your timelines: 5. Select those subclips in your timeline (on the audio track) - you can select all of them, but don't select any for which you haven't synced the audio (as per line 4) 6. Right click -> Clip attributes 7. Audio tab -> change Source Channel to "Linked Channel".
This probably only works when those files are indeed connected. In my case I had created a main clip that was synced with external audio, based on waveform and THEN I made the subclips. The external audio and the main clip were never connected outside of Resolve. So if Resolve loses its sync when opening a 16 project in 17, there is most likely something wrong with the way the internal 'linkage' is read from within the project.
Selecting the 'linked channel' from your point 7 might work, but I always thought that as soon as the subclips are on the timeline Resolve no longer considers them the same clip as the one in the media pool (it even says so in the manual) so I'm not sure if it would 'reconnect' with your method. If it works it's a wonderful workaround though.
I experienced this same thing on DaVinci version 17.2.2. The clips affected all had embedded sound recorded in camera. When using a composite clip I made from external sound synced to video I had no problem. So separating the sound and video and re-syncing them is one solution to this, but a silly waste of time really. The other, easier solution is to right click on your subclip(s) and select 'Use full clip extents' as mentioned above. This also gets around the annoying problem with subclass in Davinci where you cannot extend them beyond the exact sub clip parameters if needed on the timeline. Looking forward to Blackmagic sorting this one out. Mick