Why object disappeared when preview mode is on?

Hi @qing_3274 , Also, a Layer set not to print (Print Layer unchecked in Layer Options) will display as italics in the Layers Panel. Its contents will be hidden when Overprint Preview is turned on:

Two places to look: Attributes panel. See if the items are set to not printing. Layers panel. See if the items are on a non-printing layer.

Please provide the following screenshots:

• full page in Normal mode
• Pages panel (Window > Pages)
• Layers panel (Window > Layers)
• Conditional Text (Window > Type & Tables > Conditional Text)
• Attributes panel (Window > Output > Attributes) with the text frame containing the table selected
• and the Parent page(s)

Preview mode is meant to not show guides etc which won't be seen when the final output is produced. For the missing object check if it is a non printing object. See the defintion of the preview mode at the link below

https://helpx.adobe.com/indesign/using/workspace-basics.html#:~:text=Displays%20artwork%20as%20if%20it%20were%20output%2C%20with%20all%20non%2Dprinting%20elements%20suppressed%20(grids%2C%20guides%2C%20non%2Dprinting%20objects)%20and%20the%20pasteboard%20set%20to%20the%20preview%20background%20color%20defined%20in%20Preferences.

-Manan