OPC Tags Empty on Change

The value goes to null on any OPC tags we add or update. All existing tags, which have not been changed, have the correct values. If we create a new tag, and make it identical to an existing tag which is connected and has the correct values, the new tag is still null. This also applies to the entirety of a UDT when a single tag in the UDT is changed.

On version 7.9.4

Fixed it in the end by restarting the OPC server. Seems to be the same issue as in this thread:

However, that thread indicated that the root bug should have been fixed in 7.9.4 and later.