At first thought, the behaviour you describe would seem to indicate how Machform handles errors e.g. filling in the form but omitting required fields. The form is wiped clean and the "required" fields that were missed are highlighted in red.
If that's not the problem, then at the same time, it is strange the entries are being submitted even though you're not getting the "thank you" message. However that might be something you can actually turn off completely. Check the form properties, that you have a redirection to the "thanks" page (whether the simple message or completely separate HTML page with your Thanks message)
Regarding not receiving email notifications are you sure the email settings are correct e.g. SMTP settings - mail server, port numbers, user credentials for that email address etc.
These may all be things you have already checked; I don't know what else to suggest.
If it's still a problem, suggest submitting a formal support ticket to Appnitro (bear in mind their support hours are Mon to Fri their local time business hours). I think Australian WST is also on par with Indonesia (Java) time zone.