I have a similar problem, maybe...
My new iPhone X gets some blank messages. These messages are only on this device, there is nothing in the mailbox on server. Only when I deleted message on device, in the Trash will display it . Empty is the field from, subject, body .... for example the DisplayDate field is 08.08.2048 01:07:19 (or year 7494, 5958...) . I have a few devices on the same server, the problem is only on new iPhone X.