When I overlap Google Spreadsheet placeholders (one behind the other), and have one display from 8:45AM-4:00PM, and the other display from 4:00PM-8:45AM, the headers and data from the inactive one display anyway. Is there a way to make a placeholder completely invisible until a certain time?
Just so I understand correctly, you have 2 Placeholders, each with content that is supposed to stop running at a specific time, and they continue running? Is this happening on a Display, or just in Preview? Preview does not follow schedules or timelines, so that would be the reason you are seeing it in a Preview.
You'll notice that each Placeholder has a "visible" option, that you can manipulate with some HTML expertise. This page goes into how to hide and show Placeholders in Presentations.
We'll test your scenario above on a Display, to see if we can recreate the same issue. We'll let you know if we can. Thanks!
I've had a similar issue; I've got a Placeholder -- inside of that placeholder I have 5 sets of Text Content -- one for each day of the week, and I'd like to schedule each of those to show up only on two days a week, each.
Every time I preview, I can't see that the settings that I've made, are showing up, schedule-wise. The "wednesday" and "thursday" blocks of text should be the only ones I see, yet I am seeing all of them.