Hi Quam!
We need to investigate this further, and because it seems really client sensitive, I advise you to seek country specific support. Please take a look at the following on how to get support. Refer to this post in your initial contact.
https://community.visma.com/t5/Forum-in-Developers-Visma-net/Update-on-Visma-net-ERP-API-Support-channels/td-p/633804
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