Custom site design/site script doesn't always update the site header

ErkanCh I can confirm that I have also previously experienced this same ratio of inconsistency (failing or malforming around 20% of the time) using site designs and site scripts, on tenancies not associated with the GCC. When I did have errors, it seemed to disproportionately present errors relating to either the header or navigation. I've yet to find a reliable workaround other than moving over to PnPProvisioningTemplates instead!