I'm not sure, but I think you just have to turn on TMC again. In some cases (updates) it turn's off in my car. I don't know why. Perhaps your's, too.

Map > Information > Traffic Information > TMC (or something like that)

Everything should be gray, except the TMC word. When you choose it, the other words should turn from gray to white and the TMC sign should appear a few secounds later.