Spinning Rainbow of Death

I just upgraded my old 2014 Mac mini for a brand spankin new one. The reason for the upgrade was simple. The old machine just couldn't handle the 4K media with overlays and effects. But I never got spinning rainbow of death. Just bogged down movement. Fast forward, new Mac mini and the upgraded FCP X which by the way I didn't ask for, and now I can't pull a still or a piece of video into the time line with getting the rainbow of death. Sometimes it fixes itself most times I have to force quit and restart which is a pain in the ass. I got the 251 GB and all my media is on external drives so nothing has changed there. 
Any help would be greatly appreciated because this nonsense is bogging down my process more than the old Mac mini. Also I have tried the restart and deleting the FCP file in preferences more than a coupled of times. It hasn't helped. 

By new Mac Mini, does that mean the M1 Apple Silicon version? Re FCP upgrade, if on Apple Silicon, the OS must be upgraded because older versions won't run on that hardware. Likewise the older versions of FCP are not universal x86/Apple Silicon apps and won't run natively on the new MacOS.

A common cause of beach ball cursors is an incompatible plugin. The Apple Silicon version of FCP generally requires those plugins be re-written to use the FxPlug 4 framework, which (when done) makes them more reliable.

However some users have older audio plugins and have figured out a way to run them in a compatibility mode on Apple Silicon, which often doesn't work well. Other users managed to force FCP to run in Rosetta2 emulation mode on an Apple Silicon machine to retain use of the older plugins. That often doesn't work well either.

Another possible problem area is if a USB 3 hard drive (esp. SSD) does not use the original thick OEM cable, OR is connected to a USB hub. This may work on an older machine but not a newer one. Make sure any external USB drives use the original OEM cable and are directly connected to the Mac Mini, not going through a hub.

Any external drives should be formatted either MacOS Extended Journaled or APFS.

The fact it used to work doesn't matter in cases like this. It could be an out-of-spec condition that was never supposed to work.

As a standard troubleshooting step, if you are using any wireless audio such as headphones, AirPods, etc, temporarily discontinue that to see if it makes a difference.

Make sure FCP has permissions to all required drives. Go go System Preferences>Security & Privacy>Full Disk Access, and make sure that FCP is enabled.

If none of those steps work and FCP still hangs when importing media, while it is hung take a spindump and send me the file. This describes the overall procedure; do this for the hung FCP process:  support.kaspersky.com/15226 

Zip the spindump file and send it to me here:  www.transferbigfiles.com/dropbox/joema

Thanks for the Help. I moved the active drive from the usb hub to the direct plug in and it helped a little but I am still getting the spin. I am sending the spin dump. The Mac mini is the brand new M1 series I just got it 5 days ago.

It's a complex spindump, and I don't recognize any clear-cut "smoking gun". However here are a few general suggestions:

- Boot machine in recovery mode (CMD+R) and run Disk Utility First Aid on all drives, including both partitions of the boot drive. Reason: several threads were apparently hung or waiting on I/O. Reason to boot in recovery mode: unless that is done First Aid cannot get a write lock on the system volume to make changes.

- Temporarily disable Spotlight indexing. Method: System Preferences>Spotlight>Privacy, add boot drive and all external drives. Reason: several non-FCP MDS threads were active. That might be normal or maybe Spotlight indexes are corrupt. When finished with testing, go back to the Spotlight applet and remove all drives from the privacy pane. Spotlight indexes will be rebuilt. You can monitor that by doing CMD+spacebar and typing "index". When the progress bar goes away, it's complete.

- In FCP, disable background rendering. FCP preferences>Playback, clear "Background Render" checkbox, then delete all render files with File>Delete Generated Library Files>Delete Render Files>All. Reason: Several spindump threads were in Background Render function, and you report the problem happens when adding clips to the timeline. In case any render files are damaged, deleting all of them is best.

- In addition to the above Disk Utility First Aid procedure, use Black Magic Disk Test utility on all drives. Please report read/write performance of each drive. Reason: several threads were in MIO Mounting function which might imply a drive or permissions problem. As stated previously make sure FCP has full disk access in System Preferences>Security & Privacy.

- Export a project XML of your current timeline. Create a new library, import that project XML. That will create a new timeline which should be identical. Reason: the library consists of several related SQLite databases. If any corruption exists in those, exporting and importing the project XML to a new library might fix that. Test the timeline in the new library.

- Create a new user account, log in on that account and try the task in FCP that causes the hang. Reason: sometimes problems are unique to a specific MacOS user account.

- Make sure your user account (either original or new one) has all needed permissions to iCloud, Apple ID or any cloud-based assets. Sometimes when installing a new machine that doesn't get set up properly and apps will malfunction.

- Verify that all external hard drives are only formatted as MacOS Extended Journaled or APFS (if SSD). Reason: While FCP technically supports ExFAT, it works more reliably on Apple file systems. There are some indicators in the spindump about waiting on I/O or a multi-thread wait condition involving a read lock.