G'day Pedro. Do you mean that the kick lever feels solid at the top and won't move? If so "they all do that sir". Both mine do it from time to time. Caused by worn bushes under the kick start pinion and kicker shaft. Sometimes it frees after 1 stab, other times it might take 5 or 6 stabs to get it. If it becomes a regular occurrence it will be time to re-bush.
Cheers