PayPal Subscriptions Going to 'On Hold'

I have had several attempted new subscriptions through PayPal go on hold. I wondered if it was just individuals who did something wrong, but I am getting so many of them I wonder if my setup is wrong? My FluentCart settings say that my webhook is connected (it does not give me the URL to post into PayPal, just an ID), and says 'No further setup needed'. In my PayPal settings, when I look in the develop section, my Apps, go to my FluentCart App connection, the key is setup, but there is no web hook listed. Is this normal Shahjahan Jewel ? What else might be the problem if it is not the ones trying to sign up, but my end?