No new SEF URL's were generated anymore or saved in the database (in my case).

In configuration (Disable creation of new SEF URLs?) disableNewSEF is set to NO (and also in config.php and configuration.php, the files where the settings are saved in or originally set).

When I debug in joomsef.php (in com_sef), I find $disableNewSEF is YES ??????

So I changed this statement to comments, and now new SEF URL's are generated again.

Are the settings somewhere kept in cache etc. (I saw a static variable $instance where the configuration is saved, is the contents kept somewhere in memory/disk, so changes have no influence) ???????

NEW INFORMATION : in class config.php in function getConfig the static variable $instance is set (to save the configuration once per session). When I debug the contents of $instance I see 40 times the config object (per cycle, so this function has called 40 times per cycle). In my case the first 20 times this variable $disableNewSEF is set to 0 (false), but the last 20 times to 1 (true). So program (class) joomsef takes the value true for $sefConfig->disableNewSEF in function _storeLocation, because the value of the last object is taken from $instance (last 20 times true).

So why is it set to true (1) while it is false (0) in my configuration ???????

In program joomsef (class) you see two times the next constructions :

// Try to get the SEF URL
$oldDisable = $sefConfig->disableNewSEF;
$sefConfig->disableNewSEF = true;

.....

// Restore the configuration
$sefConfig->disableNewSEF = $oldDisable;

What is the reason for this (maybe while it is set to true, the static variable $instance has set) ?

It seems (but not sure) I have this problem only for items (producs with a parent product), but not sure (maybe not one SEF URL was generated anymore since a moment) ...