We have confirmed that in some cases, a spinning beachball may appear while loading a Final Cut Pro library/event/project with several ERA plug-ins loaded on many clips.
The reason behind the spinning beachball might be the background render feature of Final Cut Pro. When this feature is enabled, the plug-in processing will also reflect on the waveform of the clips.
When you open the project, the real-time render begins. During this process, the application updates the clip waveforms based on all the settings of the plug-ins that are loaded on the clips.
If you face this problem, the following steps will probably help you resolve it:
a) Close FCPX
b) Move the plug-ins from the Components folder to Desktop
c) Re-open FCPX
d) Open your project
e) Disable the clip or clips that has an ERA plug-in
f) Close FCPX
g) Put the Components in the original folder
h) Re-open FCPX
i) Ready! The project should be usable again. All you need to do is re-enabling the clips