What do you say about this plot to find the number of cluster for kmean or kproto for mixed data. Where is the elbow to identify? I would say 5? I have 11 feautures.
The bumps at 8 and 11 are likely just due to random initialization, and if you rerun with a different random seed, then they will be at a different k.
The elbow argument would probably suggest 3, but it is all but clear. I don't think there is a clear cut, but the values only drop as they would on uniform data.
So most likely, a) your distance function is not good enough, 2) the algorithm does not work on this data, and/or c) this evaluation does not work on this data.