no video on multicam clips after "Reveal in Browser"

Super annoying bug in 10.6.3: after I matchframe ("Reveal in Browser") a multicam clip in the timeline, both the source MC clip and subsequently the MC clip in the timeline stop playing video (audio plays fine). Skimming sometimes works in the Browser, usually not in the timeline.

This only seems to happen after matchframing (editing docos I need this feature quite a lot). See video here .

Tried, didn't fix: resetting FCPX prefs, rebooting, deleting all render files, Background rendering on/off. Blackmagic prores media, Monterey 12.4.

Anyone else?

Stooovie wrote:

...This only seems to happen after matchframing (editing docos I need this feature quite a lot). See video here ...

Thanks for posting that nice high-res screen capture. After the problem happens, what if you double-click the multicam clip in the timeline to open it -- does it have thumbnails? Can you skim that, or is it black? What if you then do SHIFT+F to find that parent clip in the event browser, is that also black when skimmed? What if you then select that clip, right-click and do "Reveal in Finder"? Is that clip where you expect on disk and is it playable in Finder? Is that clip on a locally attached drive that is formatted Mac OS Extended Journaled or APFS? 

Can you check in System Preferences>Security & Privacy, scroll down to Full Disk Access and enable that for FCP. If FCP is not listed you can drag/drop the .app file to the right pane, then enable Full Disk Access. That is an attempt to eliminate possible permission issues.

If that doesn't work, shut down FCP then in Finder duplicate the library bundle or make a backup copy of the library for safety.  Then open the main library using Finder right-click>Show Package Contents. Go into the event and delete the folders Render Files and Analysis Files. Those are not deleted by any command in FCP. It is safe to do that but do so at your own risk. Start FCP and evaluate the behavior.

If that doesn't work, export a library XML, create a new blank test library and import the library XML into the test library. Examine the behavior there. Exporting to XML causes FCP to extract all info from the internal SQL databases, translate that to XML, then do the opposite on import. Sometimes washing the library through XML will clear up some issues.

There was a previous FCP bug which should be fixed in 10.6.3, so I only mention it due to superficial similarity to your case. In that bug if Edit>Remove Effects or Edit>Remove Attributes is used on a retimed clip and adjacent non-retimed clips it may cause the retimed clip to go black. Did you retime any clips in that multicam?

I'm curious about what else is inside that multicam clip, and what is shown as the active video angle.

Could be the skimmer prioritizing audio causes FCP to mistake that as the active video angle (or switches it for particular codecs), but without a look inside the clip I'm just guessing.

what if you double-click the multicam clip in the timeline to open it -- does it have thumbnails?

Yes, it does. Angles play fine in the Angle editor. So do the underlying footage clips. Yes, it is where I expect it. Externally managed on a HFS+ drive. Full Disk Access is granted. I can delete the Renders and Analysis files tomorrow when I'm at the office. I didn't try XML-ing the entire library yet, just copy-pasting the clips from the original timeline to a new one and copying the events into a new Library (neither did fix). No retiming, straight cuts only.

Thanks for your time.

it's two video angles (prores 2k from Blackmagic) and the audio (wav from a field recorder, don't know the type). Dual-system two-camera setup I use for years. Changing order of the angles or playing with the active angle icons doesn't have any effect. Thanks.