Hi Yevhen,

I've seen the same issue before with an Huawei modem. 
It looks like not all modems can handle sending "ATE0 +CMEE=1" to the modem and pcui port simultaneously. 

Try removing this line from huawei_enable():
g_at_chat_send(data->modem, "ATE0 +CMEE=1", NULL, NULL, NULL, NULL);

Regards,
Cedric