Hi,
what is the expected outcome of locking a version? A version is immutable, so locking does not make any sense.
If I understand you correctly, the problem in your case is that a locked asset in a workflow can still be overwritten by the DAM Asset Update workflow. Yes, that's possible.
Because "locking" does not really mean "locking", it is not enforced, but rather seen as a flag. Unfortunately. And from what I understood this is a limitation deep in Oak 😞
The only way I know is to extend this workflow and check if the asset is locked before you do any changes to the asset.
Jörg