From: Chicago, Illinois
I had the same experience on India. Everything goes great until you get to Bombay. The problem, as castor alluded to, is that any heavy urban hex is impossible to take with stacking limits, unless the garrison is starving. And typically, the Allies should have 500,000+ supplies, as many as they want, in Bombay when the siege starts. And time is not on the IJA's side.
You opponent even took Socotra, which is a good move, but still fell way short, despite getting to Bombay in a pretty quick timeframe; it's probably impossible to get there in force much before the end of April, and he arrived in mid-May.
I think if you are playing stacking limits, against a good opponent, India is officially untakeable.
You can accomplish something on a limited basis however; it's still pretty easy to wipe out everyone on Ceylon, and even couple that with an invasion of NE India. But both have to be seen as more of a raid, with the objective of weakening the British Army, and/or cutting everyone off in Burma. In fact, the threat of the latter is probably enough already for most Allied players to basically abandon the Irriwaddy Plain. What a move on India would do, though, is secure the Burmese border.
But while the new stacking limits and other changes have made conquering India or Oz impossible, IMO, it makes it easier in China. This is why a new IJA strategy might be to clear the SRA, start digging, and commit extra resources in China. This is what Greyjoy did in his game vs. me, buying a bunch of tank units early for China, and keeping extra air and other units there for awhile. It's probably the way to go nowadays.