How can we check if it is a problem with your coding when you haven’t pasted up any code in your forum post? Please take note of what to put in a forum post in the Forum Guidelines .
If you have created your own user input form that a logged in site member is filling in and you are saving those inputs into a dataset, then it should not matter if the Admin of the website is logged in or not too.
Regardless of the activity of the Admin, if the user input form and the dataset are setup correctly, then all the users inputs should be saved into your specific dataset and nothing should be left out.
You can see the basics of setting up a user input form in these pages here.
https://support.wix.com/en/article/creating-a-form-with-user-input-elements
Corvid by Wix | How to Create a Custom Form and Connect It to a Database
https://www.wix.com/corvid/feature/custom-forms