Okay, so I captured the /save call's payload, and it matches what is on my screen. It actually has 3 payloads, the second one is right before i type the letter 'l', and the next payload shows the lack of 'l' and instead a carriage return or something? + the rest the characters 'ink' which I typed because I was typing out the word 'link'.
This is feeling less like a networking issue, and an issue with whatever engine is running the js editor. Maybe bad interaction with browser plugin or.. who knows.
Anyway, would sending you the request payload be helpful?