I like to use the round up feature and have my ‘main’ account set to round up into savings account.
Occasionally, some transactions don’t round up, so I send the few pence over to the savings pot.
Recently, I’ve not been able to do the manual top up unless it’s a pre-set amount using the toggle and I can’t change the amount to manually transfer. E.g - my main account is £123.45, I want to manually transfer £0.45 to my pot and I’m unable to. I can select increments of £5, but not £5.45
If you click the amount you can type in an amount to transfer to a pot.
Granted this could definitely be more obvious
Note that I can’t ‘add to pot’.
Well, I solved it. Having been banging my head against a brick wall for a week…
If I enter the custom amount and press ‘enter’ on my phone keypad, I can do it.
It was a ‘me’ problem 
I’d argue it’s a design problem - after entering the number you should be able to tap add to pot without having to press enter first. Whether that’s a monzo implementation oversight or phone OS quirk I don’t know.
