Final Cut Pro (11.0) Won't Render Video After Exporting

Restart your Mac and delete the FCP preferences again.

Normally modern Macs do not need to render footage unless it is unusually complex.

In the FCP Settings deselect Background Render in the Playback section. You need to do this whenever you delete the preferences.

I don't think you had mentioned livebarn before.

In what format are these videos from livebarn? Do they open in Quicktime Player? If so, please open in Quicktime Player, press Command-I for the Movie Inspector, disclose the video and audio details, and post a screenshot.

Depending on how these videos are encoded, you may need to transcode them - either inside FCP by optimizing (which, however, produces huge files), or in Finder: control-click, Encode Selected Video Files, and choose the appropriate size, like H264 1080 of whatever is appropriate, then import the transcoded file instead of the original.

You may want to try this with one file first and see if it helps, before transcoding a lot of files.

Please post an EtreCheck report https://etrecheck.com giving the application Full Disk Access in Privacy & Security System Settings. Copy the report and use the Add Text button to paste the result into reply box. 

Does the last screenshot show a file that you were attempting to export?

I looks like you did not let the export finish. It takes some time.

That files with a bunch of digits and letters in the name is a temporary file, and when (if) the export finishes, the .mp4 file should be populated (notice how for now it is zero bytes, which is normal when the export starts - the file is created, but still has no content).

The Background Tasks window is the right place to look. And you are right, once the Share operation is deemed to be finished in the Background Tasks, the proper mp4 file should appear with the proper size and work.

To reiterate: the screenshot showing a 0 bytes mp4 file and a growing file with a strange name is normal while exporting; upon finishing exporting only the mp4 file should remain and of course it should not be 0 bytes but about the final size of the temporary file.

I forgot to add another thing you can have a look at: keep Activity Monitor open. While exporting you will probably see FCP taking a bit more of CPU, and also a process called something like VTDecoderXPCService use some percentage of CPU. When the exporting stops these should usually use less CPU and the VTDecoderXPCService may not use anything at all.

You said everything works OK except for periodic problems exporting some of the "LiveBarn" videos. That is a subscription-based streaming service that broadcasts live and on-demand amateur sports events from various venues. Those can be live-streamed or subscribers can create clips (short segments) from full games and download these for personal use. These downloads typically have some limitations, such as being limited to 5-minute segments.

FCP does not support editing any kind of open or actively-streamed video. The file must be closed and streaming stopped before importing and editing it. It's possible in some cases you think it's finished but the file is still open or it just never was closed properly.

Before you import any downloaded LiveBarn video to FCP, make sure it is closed. It might be safer to make a copy of that using Finder, then verify you can play it and go to the end using Quicktime Player. Then import that file and try to edit and export it.

There is a built-in MacOS terminal command called "lsof" which will show if any app has opened a file. Example syntax: lsof lsof /Volumes/16TB_SSD/A7S3_vs_FX6_Exp_Test/S-Log3/JDM2116.MXF

If this returns no info, there is no app on the system which has an "open" on that file.

If it returns one or more lines, there are one or more "opens" on that file. It lists the app name of each one.

A single app may have multiple opens on a file if it is multi-threaded.

Because of the unique nature of the Live Barn downloaded file, before importing to FCP you should check it with the lsof command to ensure no other app has opened it.

FCP opens media files for "read" not "write", but since MacOS and other Unix-heritage filesystems do not have "mandatory locking," it's easily possible that another app could have the same file open for writing. If FCP starts reading from the Live Barn file and, during that process, some other app writes to it, that might cause an FCP export of that file to hang.

Never heard of "livebarn" until I googled it a few minutes ago.

I downloaded a 1080p clip, stuck it in FCP and exported it with no problems.

How much free space on the System drive? You need at *least* 15%. Where are you exporting to? If exporting to an external drive, how is it formatted and how much free space available?