Birthdays wont get saved

[taich001]

Open oncloud, goto contacts, add birthday field, enter date

Expected behaviour

date should be saved

Actual behaviour

next time you open this contact no birthday is there

Server configuration

ubuntu 16.04

Web server:
Apache

Database:
mariadb

PHP version:
7.0

ownCloud version: (see ownCloud admin page)
version | 10.0.10.4

Contacts version: (see ownCloud apps page)
v 1.5.4 published on 6 Mar 2018

Updated from an older ownCloud or fresh install:
updated