This happened to me a few days ago. Due to the fact that I've lost some my drafts in the past from page refresh (that I didn't initiate) on my phone, I've already made a habit of copying my draft in preparation to paste it whenever the page is about to change, and I do it anyway intermittently, just in case the rare automatic page refresh occurs. In this particular incident right now (of not being able to insert more quotes in a post draft), I combated this by copying the first part of my draft, leaving and heading back to the regular forum thread viewing page, then quoted desired quote directly from there, then pasted the part of my draft from earlier I had copied into the new draft (hence editing the parts together). Albeit, this was a much more complicated endeavor, but I found it was at least one way to try to get around this current error.