Unable to get sort order to change for a collection

I have a collection meant to be a photo portfolio, but no matter what I do, it doesn’t want to apply the ordering. My posts get ordered as they always have, despite changing the publish date of one of them to 2022. The docs on routes and collections seem pretty limited, but I think a collection is the right choice as I want it presented as a separate area of the site that is not part of the standard posts.

Any suggestions? I’ve been combing the forums and various blogs and not been able to sort this.

Thanks,
Bill

Version: 5.42.2
Theme: slightly modified version of Casper 5.4.8 (CSS tweaks, extra custom settings, etc.)

routes:

collections:
  /:
    permalink: /{slug}/
    filter: tag:-photo
    template: index
  /photos/convention/:
    permalink: /photos/convention/{slug}/
    filter: tag:photo+tag:convention
    template: photo
    order: published_at asc

taxonomies:
  tag: /tag/{slug}/
  author: /author/{slug}/

For the photos/convention url:
I see posts in this orde (shown with publish date):

"img_9443 2023-04-11T18:16:00.000+00:00"
"img_9440 2023-04-11T18:12:22.000+00:00"
"img_9421 2023-04-11T18:11:29.000+00:00"
"img_9416 2023-04-11T18:11:04.000+00:00"
"img_9414 2023-04-11T18:07:43.000+00:00"
"img_9410 2023-04-11T18:07:16.000+00:00"
"img_9408 2023-04-11T18:06:38.000+00:00"
"img-9405 2023-04-11T18:06:06.000+00:00"
"img_9446 2022-09-01T18:16:00.000+00:00"

Given the specified ordering I assume it should be opposite that.

Thanks @Arledia, that worked great to get them in the right order. Unfortunately, now I’m dealing with a duplicated list, but I think that is related to either a CSS issue or one or there’s some handlebar causing an odd behavior. I really wish there was some debugging or logging to get a better grip on templating and handlebars, but I’ll work through this. Thanks so much for the guidance!