@v-yuezhe-msft @bcannariato I figured it out! I was (inadvertently) using a custom report theme which changed the font color of all my fields. For some reason the color looked fine in Desktop but didn't render very well for some reason in the Service. Once I removed the custom theme, all was well. Hope this solves your issue @bcannariato.
Um... guess this may be a newb question... how do I configure the format of the "Show Data" table.
Font size / type, field formatting, column widths etc?
Related issue, date formats in the Show Data table does not comply with the source data formats