I find that often when I try to edit a post (of my own) on mobile in which I quoted someone, only the quotation is there to edit; any text that I added and posted is gone in edit mode. And it's not just a display glitch: if I click save, the post is modified to contain only the quotation, deleting any text I've added.

This is using an up-to-date iPhone 6s (iOS 11.2.5) with up-to-date Safari; it's been an issue for maybe a month or two, so dating back at least a few point releases of iOS. It happens usually but not always when I (try to) edit a post.

(I don't have access to my phone to produce screenshots at the moment.)