The relink error is a "red herring." Actual problem: If a library containing certain high-frame-rate clips is upgraded to FCP 11.0, those may show as black. It is only certain camera-specific codecs. Not affected: Sony XAVC-S H.264 100.0 fps and 119.98 fps, iPhone HEVC 1080p/120(30) fps slo-mo. Affected and tested: Panasonic Lumix GH6 UHD 4k, 100.0 fps, 10-bit 4:2:0 HEVC.
Probably affected: some type of Nikon Z9 format; codec, resolution, other details unknown. This cannot be investigated without having the clip in hand. It is vital an original, unaltered camera clip be uploaded to a file sharing site where we can examine it.
It would help if users having any 100.0 fps or higher frame rate material could put that in a 10.8.1 test library, upgrade it to FCP 11.0, then post the results.
The only current workaround is revert to FCP 10.8.1. There are two methods: (1) By using FCP backup libraries, and (2) Export a library XML in 1.12 format, then load that into FCP 10.8.1.
Normally there are FCP library auto-backups in /Movies/Final Cut Backups. Do not attempt to open those with FCP 11.0 or they will be upgraded. Instead make an immediate file-level backup of all the FCP backup libraries to another drive or folder. Then make a duplicate copy of those because opening them with FCP 11.0 will upgrade them which cannot be reverted.
For an upgraded library on FCP 11.0 which shows the black clip problem, export a library XML using the prior 1.12 XML version. Then when running FCP 10.8.1 create a blank library and load that XML. It should restore the entire library with all clips and projects, without any black 100.0 or 119.98 fps clips. You will have to stay on 10.8.1 until this is resolved.
It is easy to interchangeably run FCP 10.8.1 and FCP 11.0 -- provided you saved the 10.8.1 'Final Cut Pro.app' package in /Applications by duplicating it or copying it somewhere. It is always a good policy before a major upgrade to make a backup of all files and especially the .app packages of major applications. Sometimes there is a Time Machine backup of the prior FCP version available.
