Disclaimer: I was not the table director and did not participate in the appeal; I was DIC of the event and discussed the hand at the time of the ruling, and briefly with the Appeal Committee chair after their decision. Thus, the account that I present is based partly on second-hand information. Please discuss the hypothetical case as presented here, whether or not it is precisely what actually occurred.
EW were playing 2/1. All players are experienced, but neither partnership is well established.
East paused a long time before the 6♥ call; NS asserted about 2 minutes and EW did not dispute this. NS called the director after the hand and expressed the opinion that the slow 6♥ suggested bidding on, and that the contract should be rolled back to 6♥ making 7.
When questioned by the director, EW claimed that 6♥ showed 2 keycards with a void (clearly in spades since East had already shown shortness there with the 3♠ response to Jacoby), and on that basis the grand would be at worst on a ruffing finesse in spades.
The directors considered that the slow 6♥ did not demonstrably suggest bidding on over passing. While the BIT could certainly be based on extra values or shape, it could also have been based on a weaker hand nervous of committing to a small slam in order to show the void (for example, the same hand with Kx in each minor replaced by QJ).
On the basis that though there was clearly UI, it did not demonstrably suggest 7♥ over Pass, the table ruling was 7♥ making 7.
NS appealed. In the appeal, NS asserted that they had asked about the 6H call during the auction and West had been unclear about the meaning (on the lines of "I don't know how I am supposed to respond"). EW disputed this. The Appeal Committee also found that while EW expressed confidence that 6♥ showed 2+void, they were uncertain how to show 1+void or 3+void in their methods.