This type of issue is often due to the the subVI's file(s) becoming corrupted or being deleted. The solution may vary depending on the subVI.
- If the subVI that you are trying to add is a but built-in LabVIEW subVI, then Repair LabVIEW using the NI Package Manager. If the subVI is part of a LabVIEW module, then you should repair the module as well. For more information on repairing NI software, see Repair Software In NI Package Manager (NIPM) .
- If the subVI or its owning library was downloaded from a third party vendor or is part of a third party LabVIEW add-on, you can download and/or install a fresh copy of the third party file(s) on your computer. If the issue persists, then contact the distributor of the software you are using for support.
If you have tried the above options with no success, please contact NI Support for further assistance.