Why does Command-I show my partitions are all encrypted. None of them are

I have a 2018 Macbook Pro running Mac OS 10.13 (High Sierra). In Disk utility, the drives appear correctly: unencrypted. When I boot, there is no request for passwords. This issue only shows up with

Command-I. When I do Command-I on any of the four internal partitions, it shows them as "APFS (encrypted)" I've tried re-partitioning and reformatting the internal drive, tried reinstalling the OS, tried encrypting and decrypting a non-boot drive (the system lets me!) Command-I still tells me the partitions are encrypted.

I've spoken to 2nd level Apple by phone, and to a "genius" at one of their stores. They have no idea.

Any ideas would be appreciated!