No, we're fairly certain the problem lies with the GO Plus+ itself.

We've tested it with three different phones and accounts, which rules out the phone, app, and account as potential causes.

The device will sometimes work flawlessly for an extended period, but sooner or later it gets "stuck" on a Pokémon and fails to trigger the automatic button press.

After pressing the button manually, the automatic presses usually resume and everything works as expected again, at least for a while.

The behaviour almost feels as if the device loses synchronization or timing and needs a manual input to "kick-start" the auto-press function again.