Good find! Apparently I forgot to add pagination for this screen, so it indeed only fetches the first 50 items. I’ll see if I can fix this in one of the next releases!
Just a suggestion, fetch the subscription list using the /site endpoint to get the full list of subscriptions. Otherwise if you use /communities&type_=Subscribed there is now way to get an alphabetical list, meaning pagination would either be non-alphabetical, or you’d have to insert cells in the previous page. I hope that saves you the headache it gave me.