Bug: delay in sending emails with A/B testing

I am experiencing an issue with email scheduling when A/B testing is enabled. Emails scheduled for 7:00 a.m. are being sent at 3:00 p.m. instead.
This time difference only occurs for emails where A/B testing (specifically on the subject line) is active. Regular emails are not affected.
I have verified that the time zone for my account is correctly set to GMT +1 (Europe/Brussels).