After March update long press on harmony remote no longer works

[darwindesign]

It stopped working because you have a dongle plugged in for an OSMC remote and I modified the behavior of that key. You can find out more here…

OSMC Remote - Long Press Keymap Guide

Introduction This guide is intended to serve as a reference for users who want to modify the button behavior of their OSMC remote controls. This is not intended as a general guide on key mapping in Kodi, or a thread for general keymap questions. If you need to familiarize yourself with keymaps, or what things you can do with them your first step should be Kodi’s wiki on the subject. OSMC Legacy Behaviour The first two generations of the OSMC remote using OSMC prior to the March 2020 update …

You can turn off the custom map and the old behavior will return. Alternatively If you also use the OSMC remote and want to keep the rest of the tweaks I can give you a keymap that will return the behavior of that key.