Solution
First of all, in order to avoid the issue with the .NET version and corruption in LabVIEW, please use the LabVIEW example with the .NET Assembly DLL call.
You can find the examples by following the steps below:
1. Navigate to
Help-> Find Examples.
2. Search
.NET and open
Calling a Private .NET Assembly VI.
3. Run the VI and wait for the result.
If the example works fine without any error messages that means that the issue is related to the .NET Assembly that we are trying to call.
LabVIEW fails to show methods in cases where the .NET assembly either isn't found or is broken.
There are other reasons why specific methods might not show up (e.g. LabVIEW can't call methods with Generic parameters).
We can expect to have the same issue when the methods are inherited from an Object such as GetType().