Shelly 2PM sometimes fails to switch one of the lights when both switches are triggered simultaneously

I had to replace my dying Shelly 2.5 with a new Shelly Plus 2PM. It is running on the latest firmware and does its job switching two lamps in the bathroom. Except for one major problem: about 30-40% of the time when both switches are switched on or off simultaneously, one of the lights fails to switch off/ on.

Has anyone experienced anything similar?

Shelly support has confirmed the bug and their engineers are working on fixing it.

In the meantime, I noticed that the problem only occurs when you have an I/O action configured (in my case, one of the switches is triggering another shelly device). So, a workaround is to disable the I/O action and run it via the home automation system of your choice.