Subscriptions - 4pm always late

Hi everyone,

There is strange behaviour with Power BI Service subscriptions - scheduled every 30 minutes in period 8am - 10pm.
But every day, subscription that is set for 4pm is sent at 4.30pm, sometimes 1 minute before subscription set for 4.30pm, sometimes 1 minut after.

I tried removing this subscription, creating it again, but it keeps sending at 4.30pm instead of 4pm. All other subscription are sent on time.

What might be the reason? Has anyone had similar issues?

Cheers,

Nemanja