Have you got any default worksheet font format settings?
You can try right clicking on a worksheet and select copy formatting and applying it to the target worksheet.
Thank you your quick response! I tried copying formatting from one sheet to another, and I just tried clearing the formatting (Format-->Clear Formatting), no change either try.
Is one of them set to "entire view" maybe?
Thanks for jumping in! Both sheets are set to "Fit Width". We've played around with changing the view settings with no change.
For one of the worksheets, was the size slider inadvertently adjusted?
If you notice, there are 2 tick marks in the size slider. I don't know what the two really "mean", but I think the first one corresponds to the "true" point size of the font. Hoping a Tableau guru can hop in and confirm or deny this.