Hello,
Sorry for not answering for a long time.
I don't know why this is happening because on my phone and with the basic project, there is no problem, I choose Hexa String Mode and send 303132, I receive on the other side 303132.
Here is a version of the extension with app inventor sources updated, can you try it and tell me if it make it works better ?
com.gmail.at.moicjarod.aix (18.3 KB)