Our sandboxes updated to Version: Summer '18 Patch 3.5 on 5/5/18.  Since the update an existing validation rule is causing failures when updating the record that the rule is associated with.  The rule fires on an encrypted field and is throwing a Invalid (null).  A previous known issue I found here is similar but it says it is fixed (https://success.salesforce.com/issues_view?id=a1p30000000jaT3AAI&title=validation-rule-occurring-with-invalid-null-when-org-has-encryption-enabled).  I also tried the work around in the known issue, however the rule still throws the error.

Our sandboxes updated to Version: Summer '18 Patch 3.5 on 5/5/18.  Since the update an existing validation rule is causing failures when updating the record that the rule is associated with.  The rule fires on an encrypted field and is throwing a Invalid (null).  A previous known issue I found here is similar but it says it is fixed (https://success.salesforce.com/issues_view?id=a1p30000000jaT3AAI&title=validation-rule-occurring-with-invalid-null-when-org-has-encryption-enabled).  I also tried the work around in the known issue, however the rule still throws the error.