So I'm quite new to FTB, but I'm running a server using FTB_Utilities, tried changing the value and some code from a previous thread, my only conclusion I came to is that the ranks are configured incorrectly. Here's all the code that was in the ranks.txt file, not sure whats configured incorrectly, can give ranks but changing the maximum chunk claim limit I cannot do. Here's everything in it.
// This file stores rank definitions.
//
// [name]
// permission: value
//
// Add [name extends parent_name] to make this rank include all permissions from parent_name rank.
// Add [name is default_player_rank] or [name is default_op_rank] to make this rank default for players/ops that don't have a rank set explicitly.
//
// For more info visit https://guides.latmod.com/ftbutilities/ranks/
// To see the list of permission nodes, open all_permissions.html in browser or all_permissions_full_list.txt
[player]
[op]
"op": "op"
"ftbutilities.claims.max_chunks": 100
// This file stores rank definitions.
//
// [name]
// permission: value
//
// Add [name extends parent_name] to make this rank include all permissions from parent_name rank.
// Add [name is default_player_rank] or [name is default_op_rank] to make this rank default for players/ops that don't have a rank set explicitly.
//
// For more info visit https://guides.latmod.com/ftbutilities/ranks/
// To see the list of permission nodes, open all_permissions.html in browser or all_permissions_full_list.txt
[player]
[op]
"op": "op"
"ftbutilities.claims.max_chunks": 100