Well, it's kinda weird when you have to use a road while dtiving a halftrack being somewhat designed for offroad transportation and even can't drive up a tiny bump after stopping.
As Roughbeak says, it often works after a few seconds, but I've also seen this thing being unable to move forward at all, which forces you to reverse, gather speed and then pass the bump. Sometimes it's also good like that, because the slope is so steep that driving up it while standing seems unrealistic. Especially for jeeps and trucks.
But especially a halftrack should manage slopes without many problems, as the tracks guarantee it does not lose traction, but currently the situation in halftracks is the worst of all vehicles.