we updated with an additional hint
what was done in detail?
ensure / trace the variables and definition e.g. with:
Understanding the 6 Debugging Panels of UiPath in the easiest way possible! - News / Tutorials - UiPath Community Forum
let not mix up LINQ, Data, Flow and modellings as a correct LINQ can fail e.g.
- used on the wrong place
- used with variation of data, which are out of expectactions