As always, ensure:
- You have latest Avada and Fusion Builder
- You have latest WordPress
- You have tested with third party plugins disabled
In particular the most likely reason is either outdated Fusion Builder or running the latest Fusion Builder with an old version of WordPress. Also please note, it is unlikely you are all experiencing the same problem. So please ensure you go through all three listed above. Reverting to a previous version is not recommended.
For the colorPicker error you have shown in the message above. In that message is says WordPress is 4.9.6 (latest) but Fusion Builder is 1.1.5 (old, latest is 1.5.2). So the Avada theme version and Fusion Builder need updated.