Bug? - lots of wires are missing in the dyn file

The dyn and the corresponding Revit rvt file are generated on PC A, then copied to PC B.
When opening both rvt and dyn on PC B, it says: Revit file is corrupted; as for dyn file opened on PC B, lots o wires are missing as you can see in the above image.

The same rvt and dyn are OK on PC A.

Both PC has Revit 2021.1.20.44 and Dynamo 2.6.1.