I've made up test example (advanced.zip archive) it contains advanced example almost unchanged. I just change autoSync of CrudManager to true, and set transport url for "sync" method. And there is a serv.js file which serves as a dummy backend - it sends valid response in case of adding new task.
Test scenario:
1) unpack, npm install (it should install express js and body-parser)
2) run from command line
3) go to localhost:9090
4) Add new task (click + button on top), hit enter (do not change name)
6) Look at the network tab, there should be server response 200
5) Hit undo button
6 Look at the network tab, i do not see any requests, should it be there?
Example uses trial version 4.2.4 (our subscription expired, and we are in the process of purchasing new one)
I also tried this example with 4.1.2 and it worked differently, it sends request on undo, as i described in the first post.