Library not automatically updating [PMS 0.9.12.11 to 0.9.12.19]

Hello,
Since updating to 0.9.12.11, Plex Media Server no longer automatically updates the library when I make changes.
PMS is set to update automatically when changes are made, and every six hours, but I have to make updates manually.
My media files are stored on QNAP NAS, but due to the unreliability of the QNAP PMS, I'm running PMS on my Mac. My Mac is using Mac OS 10.11.
I've attached logs to this post.
Does anyone have any advice on this?
I've seen earlier posts regarding this issue, which have advised deleting scanner.bundle. However, that file is no longer accessible. Also, a few months ago, I was also told by a Plex tech support rep on this forum that deleting bundle files is no longer necessary - although the advice is still given in the Plex Help pages.
- Richard