OCC can only report new open interest after clearing and pairing opening and closing positions at the end of the day. http://www.optionseducation.org/tools/faq/general_information.html So I am trying to rationalize knowing that's impossible. Anyway. That's my last word. Maybe someone else will give you satisfaction.
marsman: look more closely. To satisfy your curiosity, examine the price at fixed times. For example you look prior to market open (good), but for your EOD, you have no timestamp. Look at prior to open on successive days to observe OI. Also, your data at the open is using the prior day's Volume, which adds some confusion. Google Open Interest for how it is reported!
Here are a few captures of the OI and Volume at market open and at market close. Note the OI at market open and market close remains unchanged. The OI is updated some time AFTER market close (I do not know if there is a precise time for the update). I hope this helps. (BTW: I am on Pacific time, so 6:30 is just prior to market open)
OCC has already OI=686 in its records, so IMO the overnight trades are IMO fishy... How can they trade overnight/premarket so many contracts (almost 100) without any change in Bid/Ask/Last/Volume?...:
I do NOT understand why you remain confused. Re-read what Open Interest is and how it is reported. Look at your own post above, where they (OCC) clearly state "Open interest figures are derived from ....". Unclear if overnight trading is even involved. Could be, but the numbers seem to imply most if not all are otherwise. Consider that most of yesterday's volume could be opening positions, which would correlate to the OI change from prior day!
No worry. Error ain't problematic in it-self. But its non-recognition / acceptation is worrying. And hopefully you found a satisfying solution to your problem.