Payplans 4 : Can't save pre-expiry time in Notification rule

Hi there,

I'm using Payplans 4.0.1 and Joomla 3.8.12
I'm trying to create a pre expiry notification, but Payplans don't save the pre-expiry time (whatever if I try to set an amount of days or months).
For example (see attached), if I set 7 days pre-expiry time, after saving, the time will reset to "unlimited" .
It works fine for post-expiry notification.

Thanks for your help!
Kind regards