So this should be right?

[Service]
Type=simple
ExecStart=/usr/bin/stdbuf -oL -eL /usr/local/bin/bela-cape-btn --pressed 1 --pin 86 --hold-press-timeout-ms 4000 --hold /opt/Bela/bela_button_hold.sh --delay$
Environment=HOME=/root

you have --delay$ which should be --delay 20 --monitor-click 0
In other words, the line should be:

ExecStart=/usr/bin/stdbuf -oL -eL /usr/local/bin/bela-cape-btn --pressed 1 --pin 86 --hold-press-timeout-ms 4000 --hold /opt/Bela/bela_button_hold.sh --delay 20 --monitor-click 0

    giuliomoro The --delay$ was a copy error from my Terminal (OSX). It's been a few hours of back & forth, with things like pressing button for 1 sec, resulting in patch change ... but then an immediate shut down as well, although i surely hadn't pressed 4 secs for shutdown. There's been other weird things that i'll spare you from.
    Trying between standalone and IDE or just SSH connected modes also produce different results occasionally.

    Now it functions in standalone, but not the shutdown command. For me that's good, as i wouldn't need shutdown probably. Just trying to make sure my rack is fucntional for a concert on Saturday.

    Thank you again, and for now, this week I'll create no more troubles 🙂 Enjoy the weekend.

      a month later
      a year later

      OMG I fixed it. The SD card was falling out on the back! Due I think to hitting the USB cable upon installation to the rack - Whew!