Callbackdata not being read anymore

[Etherdrake]

Some of my bots suddenly stopped working, apparently update.CallbackData now is not being read properly anymore. If I: fmt.Println(update.CallbackData()) I get nothing.

Furthermore:

if len(update.CallbackData()) == 0 { fmt.Println("Nothing received") } '

Prints 'Nothing received' although there actually is a string under the callback_data field.

Have I missed a change to the Telegram API that this function now seems broken (and should be corrected)?