Can't create more than 26 events in CiviEvents (or view on dashboard)
This answer is from @SeamusLee at Bugreport: Impossible to create more than 25 events

"I would recommend you apply the patch here https://github.com/civicrm/civicrm-core/pull/10325 There is a default limit on API calls to 25 records which is what your probably hitting here

Seamus"