Does the server freeze when removing DETAIL_PICTURE?

Question

1C-Bitrix

I delete the value of the "DETAIL_PICTURE" field, and the server hangs up. The code:

$el->update($id, ['DETAIL_PICTURE' => ['del' => 'Y']]);

When you remove the property of type "file", everything works fine. The code:

CIBlockElement::setPropertyValuesEx($id, $iblock, ['IMG' => ['del' => 'Y']]);

Accordingly, there are no errors in $el->LAST_ERROR - the server just hangs up. Please let me know what could be wrong and where to look.