I am trying to link a scale bar to the viewport scale so it automatically updates .to current viewport scale.

You'd better to use annotative scale for this. There are also some dynamic scale bars in the Blocks section - e.g.:https://www.cadforum.cz/catalog_en/block.asp?blk=21315https://www.cadforum.cz/catalog_en/block.asp?blk=2791