The default partitioning option "Erase disk" of the PureOS installer creates an encrypted swap partition. (Which is good and expected.) However, it is setup with `/dev/urandom` as the keyfile in `/etc/crypttab`.
If you suspend PureOS via `systemctl hibernate` it won't be resumed since the memory state saved to the encrypted swap partition won't be decrypted again because a new LUKS key is generated on the next boot due to the `/dev/urandom` setting in `/etc/crypttab`.