'Update cached metadata' failing to update Kobo collections

[ownedbycats]

I'm not entirely sure when the issue started, but over the past few days I've noticed that running Device > Update cached metadata is failing to update collections.

This is mostly seen when I'm using Reading List to switch out books from my TBR shortlist:

1. Have a reading list that adds and removes To Be Read to the collection column (as set in the KoboTouch config).
2. While the device is connected, remove a book from the reading list and then add another.
3. Run Device > Update cached metadata.

In the past, this updated the collections column. But now it doesn't. But the automatic metadata update upon connecting the device still works as expected.

I've checked my Kobo database for corruption and run a vacuum on it but this didn't help.

Kobo frmware and Calibre both up-to-date.

Any ideas?