My monzo account has connected before but if I log in again it's gone and have to try and re connect it. It never completes using the app, why?

Hello there.

For me to be able to assist you appropriately, I would like to ask if you find any specific error on your screen. This way, we can identify and provide you with the best resolution that fits your concern. Any additional information including screenshots is very much appreciated. 

In the meantime, we can manually upload transactions from your Monzo bank. 

Here's how: 

1. Go to Transactions, then select Bank Transactions.
2. Select the blue tile for the account you want to upload the transactions into.
3. Select the Link account▼ dropdown, then select Upload from the file. 
4. Select Drag and drop or select files and select the file you downloaded from your bank. Then, select Continue.
5. In the QuickBooks account▼ dropdown, select the account you want to upload the transactions into and select Continue.
6. Follow the onscreen steps to match the columns on the file with the correct fields in QuickBooks, then Continue.
7. Select the transactions you like to import. Then select Continue.
8. Choose Yes and Done.

Additionally, I've added this article for you to check and learn how to categorise the transactions you download from your bank or enter into QuickBooks: Categorise transactions in QuickBooks Self-Employed.

I'll be in the comments if you need additional assistance managing your bank feeds in QuickBooks Self-Employed. Have a nice day ahead!