Ugh. I’m not sure why, but Thunderbird is being a bit erratic in updating feeds. I’m not the only person that has found it. Ron Miller discovered this on Jan. 14, and then gave up on Thunderbird 1.5 on Feb. 1.
This led to the entry on Bugzilla, where it seems to be on a slow path to repair.
I haven’t quite given up, yet, but will let this stew for a few days ….