Structure blocks issue an error when using strictly the structure size coordinates. It now demands a corner block, which wasn't the case before. I was always able to use the structure size, and it would outline it when I hit detect.

It now says it is unable to detect it, but it still saves it anyway, when I try. Saving structures that were built pre-18w22c, seems to cause it to take forever to save, when it used to be instantaneous in previous snapshots. After the initial re-write, it then saves it instantly.

Also, loading doesn't work unless you hit load twice, when using strictly the structure name. You must hit load twice, as the first press only updates the structure name to be prefixed with "minecraft:"