Straight bark dries out QUICKLY. Perhaps you should try the orchid mix that contains both peat AND bark. It holds moisture a little better, especially since you tend to not water as often. Mix some perlite in too, but not half and half like most people do, because it could drain too quickly for your watering schedule. Orchids are particular about how often they are watered. In fall and winter mine can go twice as long between waterings as spring and summer. I just looked, and Miracle Gro Orchid potting mix is what I used last, mixed with perlite. I think your bark is just drying out too much. I've had orchids that have died after about a year too. And I've had others that lasted many years, still others for only months. Some types are more difficult to grow than others. Oncidiums, Brassias, Cattleya hybrids, Potinara, etc. are easier for me than phals, which tend to pout when things aren't exactly as they prefer. Miltonias and their hybrids are a bit more delicate as are a lot of the others. There are so many species of orchids, it's unreal! And the soaking is a good idea. And remember that orchids like to be fed every other watering, unlike a lot of other houseplants.
