Modpack version
Enigmatica 2 1.65a on the twitch launcher

Can the issue be reproduced?
Yes

Issue
whenever i save and quit my world when i go back in my inventory dosn't update it goes back to the save that i had a few saves before hand for example ill have a iron pick and shovel the ill play for a few hours then ill have diamond and stuff then when i save and quit when i log back in i'm back to my iron pick and shovel but everything else in the world is the same just not my inventory i am running minecraft on lan and using hamatchi so my mate can join.

This issue is most likely caused by Hamatchi, I recommend using a server instead.