iMovie 10 won't acknowledge a change to time and date in High Sierra

I don't know if this started with High Sierra or the previous OS, or the latest version of iMovie....but for some reason, when I ask it to adjust the date and time, it won't. Weirdly, sometimes it will, but other times not. This is very frustrating as I, like many, keep events in chronological order. But, if I add a clip later, even years later, iMovie sees the clip as having an origination date of when I imported the file. Previously, that was no big deal as iMovie would easily change the date. No longer.

I have tried using terminal, with mixed results. I've used the touch command and the setfile command. It actually does work as the "get info" window on my clips show it correctly. But, for some reason, iMovie continues to see a newer date.

Is there another hidden date/time stamp deeper that touch or setfile can't touch?

Is there some aspect of High Sierra that won't allow you to move the date to older dates? I think I read somewhere something that suggested that if the first "created date" was XXXX (like 2018), then you couldn't actually change the date to olderXXXX (like 2017).

Any ideas or suggestions would be so nice.