The mistake you report at 9 a.m. is a problem. The one your boss finds at 4 p.m. is a trust issue.

The same error changes category depending on who says it first. Reported early, it is work, with time and options and a fix. Discovered late, it carries a second piece of information, which is that you sat on it, and that part is about you rather than the task. Managers forgive the first kind constantly and remember the second for a long time.

Set a rule for your shifts: anything that will matter by closing gets said in the first hour you know about it. Say it plainly, along with whatever you have already tried. The relief of not watching the clock is worth more than the awkwardness.