Final Cut Pro setup

In addition to providing the Etrecheck report, please tell us if you have Background render enabled in Settings->Playback. When this is enabled, FCP renders your timeline, whether it's necessary or not. If you've left the default location of your cache to be stored inside the library and your libraries are stored on the iMac Pro drive, it will save the render files there, taking potentially lots of disk space.

FCP is very flexible, so configuring it really depends on the intended use. I can tell you how I have our systems configured but it might be different than what your needs dictate.

Background render is unchecked in Settings->Playback

Create optimized media for multicam clips is unchecked in Settings->Playback

Leave files in place is selected in Settings->Import

Create optimized media and Create proxy media are unchecked in Settings->Import

All media is stored external to the library, on a 10GbE NAS.

On the NAS, each program we work on has a folder that contains all the media shot for that program.

The FCP library is stored in the program folder on the NAS.

The library's cache is saved alongside the library on the NAS as a separate file, not stored in the library. With the library selected in the browser, Storage Locations->Modify Settings.

Some excellent free tutorials on YouTube:

Steve at Ripple Training’s 60 minute FCP tutorial overview https://www.youtube.com/watch?v=HqUP7Zgeuck

Izzy Video tutorials. Older so the UI looks different but the concepts are still correct. https://youtu.be/_jvyrnQpR1E?list=PLp5SAgbM8S87n1qvv34-PAU2zMHLlXyfb

FCP FTW: https://youtu.be/bNsJxKN_4z0?list=PLk1S35P86TzPmcjybsLUcmDmbbyzsMa4A

Jason Fredregill wrote:

'This can be done via the File menu inside FCPX'

I don't see anything in the File menu that would lead me to deleting render files. Can you be more specific? Additionally, is there a negative outcome from deleting these?

Select your library in the browser sidebar.

Go to the File menu and choose Delete Generated Library Files...

Check everything, including All Render Files.

Quit FCP.

You may have just recovered hundreds of gigabytes.

In addition to the excellent advice from Tom, Luis and BenB, your report shows you have Silverlight installed from 2018 which suggests that the OS install was migrated from another Mac. Migrating everything from another machine runs the risk of bringing along old, outdated and potentially conflicting software. The recommended way is to migrate *only* your User data, no Applications or System files. Then do a fresh install of your apps from the App Store and 3rd party developers.

I don't see anything in the File menu that would lead me to deleting render files.

Select library →File →Generated library delete file

is there a negative outcome from deleting these?

It is better to delete all old rendering files. There is no problem because the rendering file will be newly generated when you open the project.

If you truly think another one will make a difference I'll do it.

Since the cause cannot be resolved by speculation, I think it is wise to perform an EtreCheck diagnosis immediately. Paste your report in the text box and submit.

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. 

You may have run Etrecheck many times in the past and maybe posted here before, but it is still relevant now. We can't possibly remember what your report from before was.

To me it is still unclear just how the space is being depleted - is it the library? is it the system using space for virtual memory or whatnot?

And the usual things tend to appear in these reports... like chrome or cleanmymac or similar things. These can cause all sorts of problems and we have no way of knowing unless you show us.

The Apple Store I’m sure simply migrated everything from the previous system, all applications settings and files. Silverlight is old software if I remember correctly related to Windows generated files. It’s probably been carried over multiple times from older systems. It’s usually best to build a new system by migrating the user files only and reinstalling the applications you need.

It is very clear that your drive is full. 10GB out of 1TB is essentially nothing, and you risk that you mac may fail to even boot.

What is unclear is what exactly is taking up that space. Is it mostly used in FCP libraries?

Does some of that space get recovered when you quit FCP or not?

How big are your libraries? Did you delete the generated files?

EtreCheck has not solved the issue before.

You are free to refuse to post a report. No one will cooperate in return.