Hi Frederick,
Thanks for replying. That's a bit opaque to me... please can you explain:
1) "adding a system call to WP Cron" - what does this mean?
2) What kind of WP Admin activity is "not extensive enough to allow for various levels of caching"?
In UpdraftPlus's case, we set a transient that contains data about the backup run. When the run resumes (e.g. after the previous one gets killed off by the web hosting company for running too long), we use that transient to see how far the run got. In a previous version of W3 Total Cache, when we called "get_transient" to recover the transient, there was no data to be found - did you fix that in the latest release? Daniel - this sub-discussion is nothing to do with your white-screen problem, so you can ignore this digression.
David