I have also learned today that Tide does not accept paper Direct Debit mandates, despite providing an address for this purpose. It took about a month for this to actually be mentioned to us after we originally contacted support about a £10k payment bouncing.
We don’t have a single supplier who is able to process digital DD mandates at present.
In its current state, no serious company should consider using Tide under any circumstance. It is not fit for purpose.