SingleTime in forms with validation rules does not prevent promotion in approvals

Summary: For forms with validation rules that have Do Not Promote selected but also use SingleTime, the validation rules won't stop the entities from being promoted in Approvals. When I switch to the normal year and period, the validation rules will stop the entities promoting.

Has anyone else experienced this and is this an intentional design decision?

Content (please ensure you mask any confidential information):

Example: Validation form to check if the balance sheet balances, with a validation rule checking if the value >2 or < -2 that has Do Not Promote ticked. SingleTime is ticked on the form and a substitution variable used for the current singletime month & year. An entity has a balance sheet balance of 50 and so violates the validation rule. In approvals, this entity is able to be promoted to the reviewer.