I'm still getting this bug pretty frequently. I only play on Insane sized maps. After a while the sound effects just stop in battles, production screens etc. They work for the first 200 or so turns and become pretty dodgy after that. Even a complete restart of the game only fixes the problem for a little while (sometimes only one battle) and then its back again.
Anyone else still getting this? It was reported fixed back in May, but I'm not sure it was fixed for insane maps (or if map size has anything to do with it).