Possible Bug: MWI and Clock

[AMount]

I've noticed an issue with my T21P E2 and T23G running xx.81.0.110. It is not happening on my T29G running the same version.

When MWI is lit, the clock won't update. For example:

1. New message arrives at 13:21, MWI lights up
2. Five minutes later, the clock still says 13:21
3. If I lift the handset, the clock will update to the current time
4. Once I put the handset back, the clock freezes again
   

When MWI is cleared and turns off, the clock works normally.

Can anyone else confirm this behavior?