I see a few people have had this issue but couldn’t find a definitive answer. I’ve tried to reinstall the app and move payments to a new bills pot. I did notice that some direct debits don’t include the repeating subscription option. Not sure if that’s anything to do with it.
For any Direct Debits that don’t appear to have the option, look for a transaction in your main feed where money was taken instead. You need to tell Monzo that it’s a repeating transaction. This will then associate the Direct Debit with the recurrance.
(Hope that makes sense).
Just to add:
Try to pick one of the transactions that falls on the expected date. If your DD is usually due on the 2nd but you marked a delayed payment as repeating (like the 5th due to weekends and bank holidays), it will set the recurring date as the date of the transaction (in this case the 5th, not the 2nd).