Hi Jiri,
Interestingly, revisiting this transaction today (further tweaks etc) I don't seem to be able to reproduce the same issues? It's still failing (but image match appears to be to blame here). If I recreate the 'same' monitor using the same steps, I don't encounter issues, pop ups or other oddities..
I'll keep an eye on it & see how it performs & should the need arise, will get a support ticket on the go.
Thanks,
Daniel