Capella 6 - XHTML issue

When i am generating a html documentation using the XHTML addon with Capella 6, the text of the block is misaligned, see next pciture
grafik

The original looks like this

Furthermore after starting Capella 6 and pressing HTML dcoumentaiton generation the documentation is generated. If i try to do it a second time the following error message appears.

Dont know whats wrong here.

Best,
Michael

Update: The same thing happens if I export a diagram through the “export diagram as image” command