I want to personally and publicly thank Michael for helping me resolve this issue.
It turns out that I had a good number of photos with bad EXIF data (modification dates in the year 2022). The file system then dutifully set the file modification dates to the metadata EXIF modification dates. Therefore, EagleFiler was always reindexing these files (as it should) since it thought they had been changed.
What’s important to note here is not so much what the problem was - but that Michael worked with me and, with verbose logging turned on, let me track down the issue.
There are very few software vendors that will a) pay this amount of attention to an issue that it turns out had nothing to do with their software and b) have the capabilities in place with excellent logging to help track down these type of things.
Thank you for absolute first-class service. I’ve tried DEVONthink, SOHO Notes, Together, Yojimbo (oh, you want nested folders?), and others. EagleFiler stands head and shoulders above them for my needs.