It seems the source of this issue was a line of code in 'admin/settings.php' that was changed between 3.5.0 and 3.5.1
3.5.1 < > 3.5.0
line 41
< if ($data = data_submitted() and confirm_sesskey() and isset($data->action) and $data->action == 'save-settings') {
---
> if ($data = data_submitted() and confirm_sesskey()) {
This is the only change in the file.
For some reason, in our environment, the attribute '$data->action' is never set to 'save-settings', and I believe is always null. This will silently skip the block of code responsible for validating and saving admin settings if they've been changed. If anyone has any ideas why our environment in particular would never correctly set this attribute, I would be interested to know.
