I started a project in which Arduino Uno needed to be used with LabVIEW. Firstly, it is required to install LabVIEW Interface for Arduino toolkit as described in Installing LabVIEW Interface for Arduino Toolkit Using VI Package Manager. Then I followed the instructions in How Do I Load the LabVIEW Interface for Arduino Firmware onto My Arduino Uno. However, before uploading the Firmware to the Arduino, there was something that had to be done so the communication between Arduino and LabVIEW could work properly. In "LIFA_Base.ino", on the tab "LabVIEWInterface", at line 740, substitute "unsigned char checksum;" for "unsigned char checksum = 0;".
Those were some procedures that made me fix the communication problem between Arduino Uno and LabVIEW.
I hope those exchanges can help you too.