Here's my proposed reconstruction of what happened.
2017-07-05 04:31 UTC objectionable answer posted.
Soon after (maybe an hour?) I flagged the answer. Usually this is all that's necessary for something to "get disappeared" quickly. It's been a while since I've been home, so I forgot this was a holiday/vacation period in some places.
2017-07-06 02:55 UTC noticed the answer was still there, so decided to escalate. Marked for deletion, down voted, and re-flag in case I hadn't already flagged or the flag didn't "take"; however there is no such thing as re-flagging! Below is an example of what happens. A similar dialogue box opens, with a similar set of radio buttons from which to select the type of flag, and a big "action" button at the lower right, but the action is to cancel or remove the flag unless one selects a different radio button. So after 20+ hours of being flagged, the second action removed the flag and possibly removed traces of the initial flagging.
Because the moderation activity here is so speedy and efficient, I was surprised when the flag wasn't acted on quickly. In my attempt to flag again in case my first flag didn't take, or that I hadn't flagged, I removed the flag by not looking closely at the dialogue box and noticing that even though there were options, the active action was to remove the flag. Now there's no record of it.
above: what a flagging dialogue box looks like.
above: what the dialogue box looks like if you click flag a second time
above: what the reassuring message looks like if you click "Retract". Same color and shape as the "We'll look into it" message, except that it now says the opposite.