I recently updated my staging site to 4.2.8 and now all the string translations are not appearing translated any more in the english copy of my site. (Main site is in german.)
General translations from the editor such as posts and products seem to be fine.
I already deactivated all other plugins -> same thing, so it can't be an incompatibility issue.
Link to a page where the issue can be seen: It's on my password protected staging site, I'll add the credentials below.
I figured it out: On Theme- and Plugin-Localisation the box "Assume that the original language of all strings is English" was ticked.
Original language is german in my case. This solved it.