M900 ldap phonebook

After upgrading to current firmware it's not longer possible to search entries in the central LDAP phonebook.
Listing of all entries still works - But if you type any single character and press search, there are no results listed at all. 

IPDECT-V2 (M900)
IPDECT-V2/07.40/B0104/05-Sep-2024 12:36

 LDAP Server is unchanged. Older Versions and other SNOM Phones (non wireless) still work as excpected.
Is there any Solution for this issue?