It would seem that the new day starts at GMT 0:00 everywhere in the world
Not really because too many settings deal with this (unfortunately). For example India which is at a quarter of an hour offset from us, which I can’t wrap my head around anyway.
Your last d7 should be d8, but won’t be the issue.
od does not set to 1 until 10.58 when I run the closed days indicator on a 1 min chart
I readily believe you because of experiences in similar reporting (so go figure). Unless others have more sensical advices, I would attempt trials and backdoor solutions. Hence :
You are most probably right, but now what.
(no credits for me)