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
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.