How are the files named exactly? What system? What version of AE? You need to be more specific.
The files are named IMG_1000 for example. JPEG or CR2 raw files. On a MacBook Pro retina and using the latest version of AE.
Well, are there any breaks in the sequence? Do you enforce alphabetical ordering? did you perhaps "pollute" your files with non-standard metadata like named locations or redundant GPS info?
There are no breaks in the sequence, I don't enforce alphabetical ordering
and I don't think I pollute the files. I've never had a problem before, and
I haven't changed any camera settings that would prevent AE from
recognizing the sequence. It's bizarre!
Try forcing alphabetic order.
What is the exact version of AE in the Help>About section?
Can we see a screenshot of your project window with the imported image sequence selected?