Please make sure that you do not have overlapping dates e.g. start 09 February to end 09 March would create a never-ending sequence of 29-day long 'Unavailable' events that repeat every 4 weeks,
Try setting the end date to 08 March for example.
This article explains how to how to resolve the problem of not being able to create diary entries for workers/applicants (repeats) that just sit in a loop.
Please make sure that you do not have overlapping dates e.g. start 09 February to end 09 March would create a never-ending sequence of 29-day long 'Unavailable' events that repeat every 4 weeks,
Try setting the end date to 08 March for example.