Confluence has been updated to version 6.15.9

This article shows how to synchronize a checkbox custom field.  Assume you have a checkbox 'Product Choices'

Source side

Outgoing sync

 replica.customFields."Product Choices" = issue.customFields."Product Choices"

Destination side  

Incoming sync

** Collect all values of the remote checkbox and find the corresponding value
** Ignore in case the value is not found
def checkboxCollection = replica.customFields."Product Choices".
										nodeHelper.getOption (issue, "Product Choices", a.value) 
issue.customFields."Product Choices".value = checkboxCollection

See also