I have the same problem where the footing parameter lists the bottom of footing elevation as "Varies" but when I take an annotative elevation of it, it at leasts reports the proper elevation. I don't typically tag the bottom of footing elevation as other people do, so it's never been an issue for me. Not sure, maybe it's something innate with the tag?
try editing the footing type by changing the thickness to something different and then edit it again turning it back to the right thickness
Changing the thickness does not seem to help, the footing elevation only seems to vary once walls are joined with one another. If I unjoin or split them the footing elevations show the same elevation.