The twentieth century gave the Sikh community institutions the eighteenth century did not have. The Shiromani Gurdwara Parbandhak Committee was constituted to manage the historic gurdwaras and became, in practice, a representative body with elections, revenues and a public voice. The jathedars of the takhts, and the Akal Takht above all, acquired a standing role in speaking for the panth and issuing directions to it.
The sarbat khalsa has been revived several times against that background, and each revival has been contested. The argument is not about whether the institution is genuine; nobody denies that it is, and it is written into Sikh understanding of how the community decides. The argument is about who has standing to summon one, and about whether an assembly called by some Sikhs and not others is the sarbat khalsa at all or a large meeting claiming the name.
Behind that sit the political conflicts of the later twentieth century in Punjab, the events of 1984, and questions about the independence of the takhts from party politics, none of which the atlas is in a position to adjudicate and none of which is settled.
What can be described is the shape of the disagreement. A tradition that vests decisive authority in an assembly of the whole community faces a hard practical problem the moment it also has permanent institutions, because both can claim to speak for the panth and there is no third thing to arbitrate between them. That is a live question inside a living tradition and it belongs to the Sikhs who are arguing it.