This is wrong, actually. Your tag configuration is
but it should be
for this challenge since it is about "placed date", not "found date". Since it's not my tag I cannot fix this myself.
(Please note that there is a "Verify tag" button on a checker page. If you click that, the tag will be tested for the last ten people who logged the challenge as found. If all is well, they should all pass. In this case, two of them don't.)