"I scanned these images in at a date after that date"
LR has longstanding bugs with photos missing capture dates in their metadata (e.g. scans). Adobe has never prioritized fixing these.:
The core problem is that the LR catalog stores the capture date for a photo in multiple places, and those multiple values can get out of sync for scans.
To avoid these bugs, always make sure to do Metadata > Edit Capture Time on such photos. Tip: If you select a batch of photos and do Edit Capture Time then Change All, that ensures all those photos have the same date/time internally as displayed on their thumbnails in Library Grid view. Note that this does not, repeat not, repeat not change all the photos to have the same date/time. It's harmless to do this on photos for which you have previously done Edit Capture Time.
I think it's likely that the problem photos in your screenshot didn't have Edit Capture Time run on them.