Sieve stopped working after updating cyrus-imapd to 3.0.5

[rfk]

Hello,

recently I updated my cyrus-imapd installation from verion 2.5.10 to 
version 3.0.5. Unfortunately the sieve filters stopped working since 
then. The rest is working fine.

The filters are listed in the sieveshell and all incoming mails get 
tagged with "X-Sieve: CMU Sieve 3.0". However even the simplest rules 
are just getting ignored. In the logs I cannot find any related entries.

My configuration settings regarding "unixhierarchysep" (on) and 
"altnamespace" (off) have not changed since version 2.5.10 (I configured 
them accordingly in version 3.0.5). I followed the entire upgrade guide 
by the way.

Furthermore I also tried adding a completely new account with a very 
simple new sieve script (mark as seen and move to folder; created by 
Roundcube) but nothing happens to incoming mails.

Is there anything else I can check? Is it possible to raise the log 
level for sieve?

Thanks in advance.

Ralf