In a workspace, there's a view with the following filter:

AND(
{Doc Type} = "2",
{Rcpt Date} <= {Start date},
{Rcpt Date} >= {Start date} - 13,
TRIM({hdrVend #}) = UPPER({Client} )
)

The filter wasn't always producing the correct results so I started tinkering with the arguments to see what was wrong (refreshing the view and/or workspace didn't fix it). Further testing showed that editing the filter in a way that shouldn't affect the results ended up producing the expected results. For example, the above filter wouldn't work but this would:

AND(
{Doc Type} = "2",
{Rcpt Date} <= {Start date},
{Rcpt Date} >= {Start date} - 13,
TRIM({hdrVend #}) = UPPER({Client} )

)

When I would get incorrect results again, I would remove the carriage return and get the correct results.

First noticed the error at client's site and was able to reproduce at our location. Haven't tried it with sample data because the workspace uses a DSN connection for some views - this filter's view definition is from Adagio but it uses queried results from views with the DSN definition.