I thought this is related to the Error 400 fixed recently, but apparently it's not the same thing (although perhaps related). The bug has been mentioned here a couple of times already (T178748, T154116, but it would be best to try to isolate this issue.
A couple of my translations are lost in some sort of a loading loop. When clicking on a translation (say, Michael D. Coe or Nahuatl, or Caroline Sturdy Colls, all from en to pl), the CT page opens. The text I already translated appears, but it's greyed-out. The three dots on top blink endlessly as if loading the article, but the content flashes only for a second and then gets hidden under a grey overlay. I can still see the text, both the original and the translated text, but can't click it, alter it -- or publish it (the publish button is grey and unclickable as well).
The description above is based on what happens when I try to change/publish/salvage my translation on Michael D. Coe (see T178748), the exact behaviour at times is slightly different. In the case of Caroline Sturdy Colls article the original text blinks for a sec, and then both columns become simply white, nothing visible (I can see the word search and Yandex/don't translate fields, the header and the three blinking dots, but not the text). This case is interesting, as previously I had trouble publishing this article due to Error 400 (reported here). Article on Nahuatl also had this problem before (report here).
Let me know what can I do to help. Screenshots? Screencasts? Debug logs? Just point me in the right direction. Also, my full system specs and Wikipedia specs (as in gadgets and beta features) are posted in T179633.
EDIT/ More reports, possibly on the same issue (in Hebrew, @Amire80 could shed some light on what's written there): here and here