Can't say I'm impressed with this either.  I entered one bill to trial this on Thursday 2/17/22.  They pulled the funds out of my account on Friday 2/18/22,and my vendor received payment in his account on the following Friday 2/25/22.

The issue I'm having is the system didn't show any connection between the payment and the invoice.  The invoice continued to show as open and past due, and the payment was applied to the vendor's account but not to the invoice.  I attempted to reach Melio but none of the 'click to chat' options work - I tried on multiple windows, from within help, etc - none of them work.  I used the email support option, sending a request for assistance on 2/28/22.  No one got back to me.  Today, I managed to find a contact phone number within the help and called them.  The representative tried a few things with me but couldn't do anything from within QuickBooks Online.  She insisted I had to go to meliopayments.com which pretty much negates the point of having an integrated bill payment option to QBO.  She tried a few things which didn't work, then put me on hold.  While I was on hold, I got a reply to my email request from 2/28/22, asking me to confirm my checking account was the correct bill pay account.  In the 10+ minutes I was on hold (she never came back to the phone and never responded to my reply email regarding staying on hold), I was able to go into QBO and manually post the payment against the open bill.  I hung up and hopefully will have no need to use this often. 

QuickBooks Online - please improve the integration, get the support chat links functioning again, and get Melio to significantly step up their game, or find us another integration for bill pay.