I would say not Qlik caused the issue else your used driver which might not able to handle this char respectively not the charset respectively it's not properly defined. I think your specified codepages didn't really match utf-16.
I don't know if you could specify any codepage within your driver and if which ones (there might be further dependencies, for example for certain libraries to handle multibyte characters). If I had looked right on the following links the codepage 12000 seems the one for utf-16:
I assume that Qlik isn't the only tool which accessed your db. Therefore take a look which other tools or databases fetch also data from there and which driver with which specs they use for it - and then try to adopt it.
Like above already mentioned it's not a Qlik problem (Qlik doesn't execute any sql-query else only transferred the statement to the driver who transferred to the db which executes the query and returned the results per driver back to Qlik) else your used driver couldn't handle these multibyte-chars respectively isn't properly configured for it.
Given you are using our connector, the first place I would start is reviewing the Help doc to be sure you have followed the guidance there. I am in agreement with Marcus regarding his comments, I do not think we can fix the issue here, you may have to use the actual Oracle Client driver instead of ours if you need the additional functionality and submit an enhancement request for our driver in the Community Ideas area.
There are two sub topics on the Help like just FYI, would review both of those. The only other thing of which I can think is in order to process the Multi-byte correctly in the connector, you may need to be running that language version of things in order to have access to that processing, just a hunch though. The other thing I am going to do after I post this is move the thread to the Connectors area too, as that is the better place for this given the latest information, one of the engineers or product team may have a look at things at that point and shed some further light upon things potentially.
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