Daily calendar look not right

Please help us by providing the following info. Before posting please also check the pinned "Known issues" thread.
When I plan a vacation in the calendar for 21 days then I see only 2 days (start - end???). It looks like I planned for weeks instead of days.

Steps to reproduce
1. plan a vacation / trip of duration of your choice
2.
3.

Expected behaviour
Event should be visible every day defined by your number

Actual behaviour
Planning for weeks

Server configuration
Operating system: Linux Mint 18 64 bit
Web server: apache 2.4.18-2ubuntu3.1
Database: mysql-server 5.7.13-0ubuntu0.16.04.2
PHP version: 7.0.8-0ubuntu0.16.04.1
ownCloud version (see ownCloud admin page): 9.1.0
Updated from an older ownCloud or fresh install: Fresh
ownCloud log (data/owncloud.log, see https://central.owncloud.org/t/how-to-find-webserver-or-oc-logfile-enable-php-logfile/808):

Sorry, i have a log but script keeps crashing so i cannot post a log here.

Special configuration (external storage, external authentication, reverse proxy, server-side-encryption):
No

Integrity status for oC9+

No errors has be found

Locking as the user seems to have deleted his account.