You have NULLs that violate the CHECK CONSTRAINT.
To verify that this is indeed the problem, run this SQL.
SELECT * FROM integrations.accounts WHERE qb_settings IS NOT NULL OR
xero_settings IS NOT NULL OR... (fill in the fields that correspond to
those in the CONSTRAINT).
This will give you all the records that have a NULL value for any of those records which violates the CONSTRAINT.
From your SQL, you have 59 such records - that's why you're getting the error.
What you need to do to rectify this is to run SQL similar to the following:
UPDATE My_Table SET My_Field = 0 WHERE My_Field IS NULL.
Obviously it is up to you to ensure that the values that you set correspond to your system's business logic and other system requirements.