http://codex.wordpress.org/Transients_API
This page contains the technical documentation of WordPress Transients API, which offers a simple and standardized way of storing cached data in the database temporarily by giving it a custom name and a timeframe after which it will expire and be deleted.
For testing what I did was to use the Adminer plugin (phpMyAdmin) and just deleted the _site_transient_update_plugins database option. I should have been more clear about this statement – “it is automatically recreated by WordPress.” That may or may not be true and it could have been created by BPS or another plugin (set transient).
Transients should also never be assumed to be in the database, since they may not be stored there at all.
So what is more likely since this is not a standard static DB option is the real problem is that something (a plugin or theme) is blocking “set transient” actions.
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