Bug: Sender Name/Address not avail when kopano-contact gets deleted in UCS

Howto to reproduce:

Add random sender as kopano-contact via UCS to address-book (email = bla@blupp.de Last name = BLA BLUPP)
Send e-mail as bla@blupp.de to kopano mailbox.
Check mail in inbox and see sender is BLA BLUPP bla@blupp.de
Everyting fine so far
Delete kopano-contact BLA BLUPP
wait a few seconds (resync timer whatever / reload inbox)
Check Mail in Inbox again - sender is now BLA BLUPP

No email address visible anymore. And replying to this email is not possible with “reply” anymore. No email address is copied into TO: Field.

Kopano support says it can not reproduce. I can on all of our kopano/UCS-Servers.

Can anyone please test as well?

Now confirmed by kopano support.

Ticket created by support: https://jira.kopano.io/browse/KW-2384