@jelle-burodeng what's the opening {exp:channel:entries template code that you have?

Also to make sure, the entry status is "open" but with entry date in the future? And you need to re-save the entry in order for it to show up?

As well, is there any caching involved?

it's an embed:
{embed="includes/.etalage" limit="8" sticky="yes" archive="no" start_on="-2 weeks" show_link="yes"}

{exp:channel:entries
    channel="nieuws|video"
    status="not closed"
    search:alleen_op_nvjnl_plaatsen="IS_EMPTY"
    sticky="{embed:sticky}"
    limit="{embed:limit}"
    start_on="{embed:start_on}"
    category="{embed:category}"
    dynamic="{if embed:archive == 'yes'}yes{if:else}no{/if}"
    disable="member_data|category_fields|pagination"
    cache="yes"
    refresh="36000"
}

the entry status is "open" but with entry date in the future? Yes.
And you need to re-save the entry in order for it to show up? Yes.

Any word on this @intoeetive ?

@jelle-burodeng - sorry, somehow this came out of my radar.

So I see in your code that you have caching set to 10 hours. If the cache for the page was re-build close before the date when entry was supposed to go live (or expire) it will still be shown up for almost 10 hours - until the next cache rebuild.

Updating the entry clears the cache, but if you don't touch the database - the system will just serve whatever it has cached

So if you need the entries to go live/expire at exact time, you need to no cache at all, use smaller caching period or clear the caches at desired time