This behavior is the same whether header images are placed directly in the files folder, or uploaded via Media Manager (according to the new instructions). It does this with a single header image file as well as multiple image files, rotated or not. (Yes, files that reference /wpmu-settings.php were changed to /wp-includes/ms-settings.php and I also tried using is_multisite(), with same results.)
If rotated with Javascript, the #header background image url will list files that don't fit the pattern, atahualpa_header_x.ext, but the rotated files in ul/list-items may be correct.
If using a single header image, or multiple images not rotated with Javascript, incorrect images with filenames that don't fit the pattern, atahualpa_header_x.ext will be displayed in the rotation. Images on the primary site will always be incorrect.
With a single-site installation, version 3.7.6 works fine. I rolled back from 376 to 367 on multisite, except for a test web with no plugins. If you paste the 376 bfa_m_find_in_dir.php contents into the 367 version on a multisite that's working fine, you can also replicate the problem.
I've been using Atahualpa for several years and this is the first time I've had a serious problem, so I'm optimistic about a fix.
