Interpolation does not work correctly in Easy Chart and "system.tag.queryTagCalculations()"

Good afternoon.

In Ignition 8.0.14, I have configured a tag to history with this Tag Group (Scan Class):


When I query the tag with “system.tag.queryTagCalculations()” to know its “DurationOff”, the function returns fewer seconds if I ask from 6 AM to 13 PM than when I ask from 6 AM to 10 AM, for the same date. This doesn’t make sense and is very confusing.

Something similar happens with “Easy Chart”. One interval shows the value 0 from 6 to 10 and the other interval has no value from 6 to 10:

Best Regards.