Problems with small fonts

Hi, there,
I’ve installed the version 1.5.0 and I stumble upon this behaviour:

There’s an Excel sheet with text in one cell. The orientation of this text is bottom-up, the size is 6pt.
This Excel sheet is embeded in an Access form

After converting this into PDF, it looks like there’s a little black box, hiding the text.

This occurs only if the text orientation is bottom-up AND size=6pt: With 8pt, the text is shown The text is shown, too, if the orientation is “normal” (left-to-right)

Any clue?

Best regards,

Martin

PS: The blck box does not appear, when printing the Excel sheet alone.