I attempted to change the display name of a single chest with

/data merge block -20 56 14 {CustomName:"test"}

Doing so resulted in the error "An unexpected error occurred trying to execute that command" being posted to chat, and hovering over it shows "com.google.gson.stream.MalformedJsonException: Use JsonReader.setLenient(true) to accept malformed JSON at like 1 column 1 path $"

If the "test" is replace by " ", then the bug no longer occurs, with chat reporting that the command was successful, although the displayed name of the chest does not change.

Renaming a chest in an anvil, however, will still change the name correctly.

This bug occurs in both of the worlds that I tested it in.