Thanks to Drew and Ronald.
Everything is good now after doing the below steps.
1. Open Inventory Manager.
2. Highlight the switch and then change to the Image Information tab on the right.
3. Select the original ExtremeXOS TFTP script from the MIBs and Script Overrides section.
4. Click the View button.
5. Copy the script and paste it into a new text file.
6. Change the name and description at the top of the script.
7. Change the@receive 5 to@receive 15 in the configuration archive section
8. Save it to the NetSight server in /NetSight_Instal_path/NetSight/appdata/InventoryMgr/properties/devicefiles
9. Select this new script for the Configuration MIB section of the MIB and Script Overrides.
10. Click the Save button in the upper right.