Solution
This issue is a known bug (895068), that a fix was implemented for in VBAI 2019 and later.
The fix is not enabled by default, and can be enabled by placing the correct token in the .ini file.
To enable the new code path that should fix this issue in VBAI 2019, add the following line in the [Settings] section of the Vision Builder.ini file on both the Windows and (if applicable), on the target side as well:
Use_OPCUA_MultiWrite_API = true
On Windows, the Vision Builder.ini file is located in C:\ProgramData\National Instruments\Vision Builder AI\2019
On the RT system, the Vision Builder.ini file is located in etc\natinst\vbai