I was playing in a moded server and 1 time i laged and after i lagged the backpack didnt work again everytime i try to equip a backpack it doesnt work it doesnt say anything i just doesnt work when i click on the equip button it doesnt equip it just closes the backpack gui and do nothing
Am using the 1.12.2 version of the mod with custome modpack i made

i fixed it

How did you fix this? I have encountered this issue and the only way I can figure out is deleting the player data.