Steps to reproduce:

1. Open host items list and select items for mass update.
2. Check "Custom intervals" on mass update form
3. Type Interval -> 50 and Period -> 1-7...,;10:00-09:00
4. Press submit button

Result:
Message about successful update, but if open the details of message you can see that: Invalid interval "1-7...,;10:00-09:00".
Expected:
User stay in mass update form with error message.