And fail them Venice did.

The Venetians had received a reply from Louis XII to that letter in which they had heaped odium upon the Borgia and shown the king what dishonour to himself dwelt in his alliance with Valentinois.

Their criticisms and accusations were ignored in that reply, which resolved itself into nothing more than a threat that "if they opposed themselves to the enterprise of the Church they would be treated by him as enemies," and of this letter he sent Cesare a copy, as Cesare himself told Macchiavelli.
So, whilst Valentinois in Imola was able to breathe more freely, the condottieri in Urbino may well have been overcome with horror at their position and at having been thus left in the lurch by Venice.

None was better aware than Pandolfo Petrucci of the folly of their action and of the danger that now impended, and he sent his secretary to Valentinois to say that if the duke would but reassure them on the score of his intentions they would return to him and aid him in recovering what had been lost.
Following upon this message came Paolo Orsini himself to Imola on the 25th, disguised as a courier, and having first taken the precaution of obtaining a safe-conduct.

He left again on the 29th, bearing with him a treaty the terms of which had been agreed between himself and Cesare during that visit.