Hello,
Honestly, I didn’t have so much time last year, and the last thing which I did (when first angry comments start to appear) is to use more fresh WordPress core version, so the last update was aimed at WordPress version ~4.5 and newer, and (which I really not expected to have) it broke a lot of old themes. Because of lack of time, I didn’t find a normal way to support old and new themes (in old core it was impossible to use more than one plugin which changes the menu looks since many themes have their one’s plugin sometimes didn’t work because of conflict). I’m keeping in mind one way to add support for an old theme (I have it in git, so it’s not lost).
I’m not trying to ruins it, but it wasn’t my top priority in life, and with more than 80 thousand active installations, no one proposes me any help with support of this. And I’m not asking for any payment and not providing pro versions, because it should be totally free.
Don’t take it to close, I’m just upset because of lack of time to support it well.
Btw, I’m still answering people on email (even help them with code from time to time) and one day I will have time to answer to all opened issues here.
So, if you interesting in supports such a good plugin, you can send a PR https://github.com/zviryatko/menu-image/, I have auto-tests and it’s still check compatibility with the latest WP version and default theme https://travis-ci.org/zviryatko/menu-image/