Object Cache Pro, the caching plugin recommended by Pantheon, includes its own interface with a ::flush_runtime() method that clears the in-memory cache.
The default method of resetting the cache in \Alley\WP_Bulk_Task\Bulk_Task::after_batch() relies on access to the WP_Object_Cache::$cache property, which isn't made accessible by Object Cache Pro, so the attempt to write to it generates an error.
Object Cache Pro, the caching plugin recommended by Pantheon, includes its own interface with a
::flush_runtime()method that clears the in-memory cache.The default method of resetting the cache in
\Alley\WP_Bulk_Task\Bulk_Task::after_batch()relies on access to theWP_Object_Cache::$cacheproperty, which isn't made accessible by Object Cache Pro, so the attempt to write to it generates an error.