I suppose, the locator of the TestObject "Object Repository/Page_Rcapitulatif de vos tches/span_Gestion du travail" is not pointing to the HTML element of your interest.
Please check the locator (XPath or CSS Selector) against the HTML source of your web page.
I guess, you created this TestObject using the Record Web Utility built in Katalon Studio. Yes, the tool does help you, but please be advised that the tools does not always generate 100% correct codes. You should not trust the tools too much. You are supposed to examine the generated materials and correct them as appropriate.
In order to inspect web pages, you may want to use DevTools of Browsers
If you want to study the XPath technology from the bottom up, please read this: