Formula works most of the time but no always

When a new license plate number is entered in a new report (Form view), I want to show the dates of any matching license plates in previous reports. This needs to update without sync - the app is setup to work off-line which is the norm for our users who work in the forest.

I’ve setup a virtual column ,LongText type, with the following formula:

CONCATENATE(SELECT(NRC Reporting[Timestamp], ([License Plate #] = [_THISROW].[License Plate #])))

The expression assistant warns: “Note, this expression could significantly impact sync time.” But this works perfectly 70-80% of the time. It work off-line and doesn’t matter how many matches are found. I can’t find an underlying reason when it doesn’t work.

Any help would be appreciated.
Bob Haizmann

What is the difference when the formula works and when not?

Here’s an example using the same license plate number. In the first pic the match is not working. It returns a date that may or may not be a match and incorrectly shows a date format only. Then I entered a different license plate to reset the search input. Next for the second pic I re-entered the same license as the first pic. The the match works correctly and shows Datetime format as is expected.

Not%20Working Working

Should I try a different formula or not use a virtual column? A little more clarity on the problem. When the formula doesn’t work it always brings in only one date and that date may be wrong.


When you are Online, does this functionality work always?