To deal with such a problem, add an offset in the in the settings for the Contact node. The offset should be defined by a parameter, so that the boundaries of the two domains are barely in contact in the initial state. Now, the offset can be reduced to zero step-by-step, using an auxiliary sweep in the solver.
When working with a nominal geometry, you always need to add an offset in the Contact node. The offset equals the size of the interference. If needed for convergence reasons, ramp up the offset using an auxiliary sweep in the solver.
To model self-contact, include the same boundaries in both the source and destination selections of the Contact Pair definition. This will cause the boundaries to act as both source and destination in the contact search and mapping. For mechanical contact, this results in a symmetric contact formulation, as the contact conditions are formulated on both sides of the contact pair.