FCP 10.8 - All I get is the spinning color wheel of death

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. 

Try resetting FCP Settings/Preferences. Hold command and option while launching FCP. Choose Delete Preferences... and FCP will open in its default state. Remember to set your Settings back to the way you like them (disable background rendering, etc.).

Get the free app FCS Remover from Digital Rebellion, it will wipe FCP from your system totally. Moving it to the trash is not a complete removal. But I'd do that. Then reinstall FCP from the App Store.

It may not be causing the present issue, but it is well known that these google keystone "things" at times hog the system videotoolbox and hurt video applications terribly.

User Launch Agents:

[Loaded] com.google.GoogleUpdater.wake.plist (Google LLC - installed 2024-06-17)

Command: ~/Library/Application Support/Google/GoogleUpdater/Current/GoogleUpdater.app/Contents/MacOS/GoogleUpdater --wake-all --enable-logging --vmodule=*/components/update_client/*=2,*/chrome/updater/*=2

[Not Loaded] com.google.keystone.agent.plist (Not signed - installed 2024-03-07)

<Empty>

[Not Loaded] com.google.keystone.xpcservice.plist (Not signed - installed 2024-03-07)

<Empty>

Follow the instructions at https://chromeisbad.com for all the locations to look for files to remove.

Have you rebooted the machine? Does each volume on the machine have at least 20% free disk space?

Do you get the spinning wheel when you start FCP, when you open a library, when you open a project, when you select a clip in the browser or in the timeline? Once it happens, is it intermittent or non-ending? Is a specific action required?

If you close that library and create a new blank library, does it happen then? If you import a few clips to that library, does it happen then?

Are you using any third-party FCP video or audio plugins?

Please describe exactly what you mean by not working again.

Are you using a trackpad?

Are you able to launch FCP with the option key so it doesn't automatically open a library and then create a new library and successfully work with it?

Post a fresh Etrecheck.

I see this report on fcp dot cafe about Decklink and FCP 10.8.

https://github.com/CommandPost/FCPCafe/issues/362

There are font related crashes in the report. Perhaps you have a corrupt font? I've heard that can cause trouble with FCP.

Terry: great find!

eyeRuss: What type of Decklink interface is this? You have an M2 Ultra Mac Studio, which obviously cannot accept a PCIe card directly. Is it a Thunderbolt-connected device like the UltraStudio 4K Mini?

If you used a PCIe card in some kind of outboard chassis, what are the specifics?

I wonder if it's related to the hang problem just reported by Matthew O'Brien in his latest Youtube video. In his case it began on 10.8 when he clicked on an on-screen control for a title or when he used the built-in Draw Mask effect. I think he has numerous plugins but I don't know which ones. I cannot reproduce it on my similar Mac Studio machine, but I have very few plugins.