Asian characters in "Real Time Preview" (InternalPreview) flipped left by 90°

Dear community,

We are experiencing issues when real-time previewing Asian text in our Bilingual Filter Extension. In the InternalPreviewWriter for the method "Text", we just forward the target segment text to the interface:

public override void Text(ITextProperties textInfo)
{
_preview.Write(textInfo.Text);
}

Also the temp html file written looks good:

<span id="1" onClick="window.external.SelectSegment('587e4507-c03c-4d16-afd2-9f9b17e88000','1')" >ホーム</span>

However, in the integrated preview window in Studio, all three Japanese characters are flipped by 90° to the left.

Would somebody be able to help?

Best wishes,
Simon