Problem:
When the customer tries to update a person's records using Toolset, they get an "update failed" message and a fatal error Uncaught TypeError: array_diff on toolset-blocks/backend/Services/ViewParsingService.php
Solution:
This is likely caused by inconsistencies in the DB. More specifically, the meta field _wpv_contains_gutenberg_views in postmeta should contain only empty values or arrays, if there's a plain number in there this error can happen.

You can check it using:

SELECT * FROM `wp_postmeta` WHERE meta_key='_wpv_contains_gutenberg_views'

And eventually apply the needed patch.