Hi @Gwendolyn Reede-Lijding, Ebenezer here from Engineering Support👋.
I understand that we're having some issues with your end-users accessing your .xlsx files that you are attaching within messages ! I can see on our end that there is an ongoing issue regarding attached files producing an error message when opened ! Our Product Engineers are actively investigating this issue ! I will add your case to our notes and once we have a resolution update, I will be sure to notify you here ! Thank you for your patience and understanding through this matter 😄