Check that you have the categories plugin installed on the blogs where it fails.

Also, I *think* you have to make sure that you have "include in public bloglist" ticked for the blogs .... but don't quote me on that one ;)

¥

It was installed, but I uninstalled it and re-installed it to test... no dice.

"Include in public bloglist" was also already ticked... and I "unticked", saved, re-ticked, saved... no good either.

Baffling problem, eh?

I was close, this is the post I was thinking about :
JRagg wrote:

This may sound silly, but check your Blog Settings > Display and make sure that "Display public blog list:" is checked.

I had it unchecked in 0.9.2 and my categories showed, but when I updated to 1.9.3 they disappeared. After hours of banging my head into a wall I found a similar problem listed here. Checking that box brought them back.

¥

Can you test if you suffer this problem with the 'custom' skin and your feed-mod? Shouldn't take but a few minutes and you can change back to your skin immediately, and will tell if it is something about your skin or something about your installation.

A little bit from colomumn "A", a little bit from column "B"... call it a hunch, but it was a database bug.

When I enabled "Allow user customized CSS file for this blog", POOF! They're back...

Any guesses as to why?

Double Decker Bus Guy wrote:

A little bit from colomumn "A", a little bit from column "B"... call it a hunch, but it was a database bug.

When I enabled "Allow user customized CSS file for this blog", POOF! They're back...

Any guesses as to why?

Yes, this just happened to me too! My categories vanished so I tried what you said double decker and poof! They're back again! Thanks

I don't allow user customized css and I have categories showing. Not sure why others would seem to think this is a solution, but it's not required that it be enabled.