Hi @sanchezwalter , a similar issue came up in the post below from last year. Does the workaround suggested there help in your case?
Specifically see this post on that thread…
I can’t determine if this will work in your case but take a look and let us know. Also, which version of KNIME are you using? The “workaround” used a piece of java to choir or xls sheets, and the code there is likely to work only with specific versions of KNIME as the supplied libraries change with different releases.