Lots of stuff has been changing in Drupal 8 recently. In 8.3.0, a new experimental "layout discovery" module was added to core, which conflicted with the contrib "layout plugin" module. Now in 8.3.3, the two-column and three-column layouts had their region names changed, which hid any content dropped into those regions when those layouts were used.

In the past week, we've seen a couple issues upgrading a site from 8.2.x to 8.3.2, and now another issue with 8.3.2 to 8.3.3 that seem worth a quick mention.

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