Do you use richfaces 3.0.0 or one of the 3.0.1 snapshots (the same question about ajax4jsf) ?
Ajax4Jsf 1.1.0, RichFaces 3.0.0, Facelets 1.1.12, JSF MyFaces impl 1.1.4, Jboss seam 1.2.0
Try 3.0.1 and 1.1.1 snapshots. The similar problems were fixed there.
I've tried with the yesterday (Apr 23) snapshots and the problem still happens.
Some more curious information:
If I set to "true" the immediate of the correspondent rich:tab, the action listner is executed in the immediate mode (APPLY_REQUEST phase). But then this causes many others side effects and strange behaviours.
Any ideas or any workarround?