Universal Credit failure to pay final months rent

Rent Arrears

I wish to seek your advice on rental arears from a tenant claiming Universal Credit.
The tenant who rented a room in a flat share, of four years good standing was unable to pay the rent in April this year due to the pandemic.
He sought and obtained Universal credits, they apparently pay in arrears and made three full payments for May on the 6th of June, for June on the 7th of July, for July on the 8th of August.
The tenant decided he wanted a flat of his own (as Universal Credit are paying) and decided to move out at the end of August. He informed Universal Credits that he was moving.
Universal credit wrote to me on the 03rd of September informing me that no more payments would be made as my tenant had moved out.
This has left me without payment for April and August, if universal payment are paying his rent are they liable in any way for the August payment or do I need to take action against the former tenant?
Thanks for you advice