I would create a variable for the Today() function in the laod script:
LET vToday = Today();
For the expression i believe you had your ClaimNotifyDate field in the same expression as today function.
if (ClaimStatus = F , StatusDate-ClaimNotifyDate ,$(=today() - ClaimNotifyDate)) as'Days Open'
if (ClaimStatus = F , StatusDate-ClaimNotifyDate ,$(vToday)-ClaimNotifyDate) as'Days Open'
Something to worry about here is that you want to have your date fields recognized as date fields. So you still may have issues returning proper data and that;s most likely due to the format of the date fields you have.