There are many possibilities for your inventory is not get synchroized, You can follow this guide to find out who adjust the inventory and when the inventory is adjusted.
1a. In Connected Inventory, go the group/bundle which you found issue, and click “view inventory history”
1b. In Shopify, click on the variant that you would like to check the inventory, and click “view inventory history”
2. Column "Adjusted by" show you who who adjust the inventory.
i) Third Party App / staff.
ii) Normal order. For example: Order created (#xxxxx)
iii) For the inventory adjusted by our app, “Connected Inventory” will be marked in the Adjusted by column.
However, if you have tried all the options and still can't find out the reason of the inventory adjustment, message us in the app or just email our support team at support@inscoder.com with below information to speed up the investigation
1) Please provide your store URL (?????.myshopify.com).
2) If you have set up the collaborator request code, please also let me know.
3) Group Name or Bundle Name.
4) Order No with Synchronisation issue.