FCPX Cache Keeps Growing--monstrously

Hey Folks:

Never had this happen before--my cache keeps growing exponentially. I've got a 2.75 TB 4K project on an 8TB drive. The cache keeps growing--to where my drive filled up--5TB of render files. The culprit is the render files. Specifically, the files FCPX is generating the Cache>Render Files>High Quality Media.

I deleted all render files two days ago--and now the cache is nearing 1TB and growing. Yikes!

I am not currently optimizing media or creating proxy files. The bloated files do indeed seem to be render files in the Cache package.

Thoughts? Never seen anything like this--where the size of the render files keeps growing and exceeds the size of the media~

Help stop the monster!

Thanks.

Delete the render files for the library, and in FCP Playback preferences switch off background rendering.

Yes. Have done so. Just wondering why this particular project is so unusual in that the render files actually exceed the entire size of the library--that seems different.

Thanks Tom!