It would be great if someone who experiences the issue created an official Plesk Support ticket and then, once Plesk has solved it, reports back here. This must be examined on an affected server. Obviously not all are affected, so it remains unclear what causes the issue.
Question How to get support directly from Plesk? Answer Lease-type Plesk licenses purchased directly from Plesk running on supported Plesk version include full free support. Perpetual-type license...