You changed your Viewport Scale, and now you can't see your plant labels.
The issue you are experiencing is the result of a rare scaling bug.
If you have a feature called Annotative Scaling enabled, Land F/X consequently creates a scale for you. If you set a different viewport scale, the system essentially becomes confused.
Follow our steps to turn Annotative Scaling off.
You should now be able to select any scale and the system will correctly scale your labels.
The only reason you should use Annotative Scaling is if you want to display the same plan at multiple scales. If you do not need to do this, a better practice would be to define your scale before placing labels. You can always change the label scales manually by selecting Rescale Objects in the ;Viewport Scale dialog box if, for some reason, you decide to change the scale later in the project cycle.
For more information on best practices when setting the scale, see our Set the Scale page.