I think it’s become a common misconception that India and Pakistan are at loggerheads about the pipeline. In fact that is not true. Yes, there are issues, but most of those have been resolved.
The biggest stumbling block are not Indian and Pakistan not cooperating. To the contrary, it is Iran that is the main issue here. Iran insists on a prepayment for the supplies, which are above prevailing market prices, and the payment would be taken whether the supplies are delivered or not. Secondly, the supply would be a lean supply, and would not contain any petrochemicals. Again something that overvalues the gas.
The cost of the pipeline has to be eaten by India and Pakistan. Both countries see the instability in Iran as counterproductive to their respective economies.
India is very keen to move forward with any sort of economic deal with Pakistan, hence this proposed pipeline.