I couldn't reproduce the issue you mention. Can you please tell me the steps you performed after installing Q2A from scratch in order to reproduce the issue here and find a fix? That would simplify fixing the issue.
Make sure to use this version
https://github.com/pupi1985/Q2A-Infinity-Theme/archive/master.zip (I've changed a small thing but should be unrelated I think).
You could also add some debug information in file qa-plugin/Infinity-Plugin/it-layer.php, right before this line:
$count = count($this->content[$form_name]["fields"]);
Add these lines:
if (!isset($this->content[$form_name])) {
error_log('Template: ' . $this->template);
error_log('Request: ' . $this->request);
error_log('Is POST: ' . qa_is_http_post() ? 'true' : 'false');
foreach ($this->content as $key => $e) {
error_log('[' . $key . '] => '. print_r($e, 1));
}
}
That should give a lot of information in the logs.