Is Numeric, Is Digit & Regular expression function is not working properly

Activities Is Numeric, Is Digit and “system.Text.RegularExpressions.Regex.IsMatch(“variable”^\d+$”)"
are not identifying properly the numeric value Zero in string captured from scanned PDF document. Randomly it works. Please suggest.

@sballav
can you please verify the output string from scanned PDF document as the activity you used for extracting the data from PDF is not be working as expected.
whats the activity you have used to extract the PDF document.

Could you please provide more details, such as a sample, new UiPath project that reproduces the issue?