Sometimes inventory databases can get corrupted for different (and not always obvious) reasons which can cause erratic behavior of the software. The best solution in such cases is to create a new database using the inventory from the current one. To do this follow steps below:
NOTE: Steps 1 and 5 are applicable only if you are working on FBA shipments at the moment.
1. Register any Local or Working shipments you are currently working on - open each shipment and click the 'Register Shipment' button, then choose to register as "Working" (this step needs to be done only if you're on Local mode);
2. Click File > Compact database, then click File > Backup current inventory, and save the backup file;
3. Go to File > Database Manager, create a new database, then open it;
4. Click File > Restore from previous backup, browse to the location of the backup file and open it;
5. Last but not least go to FBA Shipments Manager, select the 'All Working and Local' tab, then click the 'Retrieve from Amazon' button to import the shipments you were working on in the old database. All you need to do now is add these shipments to the Shipping Session tab to be able to continue adding items to them.
If the inventory database can no longer be opened you can try compacting it from the Select Product Database window:
• from the Select Product Database window open any other existing database or just create a new one;
• go to File > Database Manager, highlight the database that won't open;
• click Manage > Compact selected database.
If that doesn't help your only option is to download your inventory from Amazon in a new database.