Solution
When an interface is placed as the first parent class in a project using Actor Framework, the Actor Framework menu item disappears and only reappears when the interface is renamed so that it is not the first item in the project window and the project is saved. This issue also occurs if you have an actor class in your project, and that actor inherits from (among other things) an interface that lives in a PPL.
In order to fix this issue, you can apply a patch to replace the VIs that cause this unexpected behavior. Please follow these steps to apply the patch:
1. Download the zip file from
this link and extract the files to a folder.
2. Back up the files that are going to be replaced by copying them to a folder.
3. Copy the extracted VIs to the appropriate folder following the same hierarchy.
- VIs that need to be copied to C:\Program Files (x86)\National Instruments\LabVIEW 2020\vi.lib\Utility\LVClass:
- Is Class Not Interface Without Loading.vi
- Read Class Ancestry Without Loading.vi
- VIs that need to be copied to C:\Program Files (x86)\National Instruments\LabVIEW 2020\resource\Framework\Providers\MessageMakerProvider\_Message Maker\_support:
- Inherits from an Actor.vi
- Is Actor Class or Interface.vi
- Is Path to Actor.vi
4. After copying the files to the correct location, restart LabVIEW.
Note: Be sure to back up the original files before replacing them with the modified files in the zip file. This LabVIEW patch can be applied in LabVIEW 2020 or 2020 SP1 only, the issue was fixed in LabVIEW 2021 and later.