Cant cast spell on Arena

What you were expecting to happen, and what actually happened?
Started Arena (with random creatures, not pvp) battles, won some.
On 3-4th game, after some moves (probably I even cast some spells) with no particular reason heroes windows doesnt respond – cant cast spells/cant check statuses/cant see enemies spells, whatever – left (and right and middle) click on all 8 windows do nothing. Still, I can move gems and gain mana/do dmg with skulls and (ofc) enemies can cast anything.

What are the steps to make it happen again?
Met this bug twice on 3rd and 5th game for example, i.e. not in a row. Cant attach any screenshots, doesnt thought about this, but still, there was no special visual effects – as usual windows changed to weapon/skills if mana requirements satisfied.

Do you have any screenshots or video you want to share with us so we can see the problem? Attach them to your post!

Steam, Win7.

This has happened to me twice, on Steam with Win10.

Clicking on any character, mine or opponents, has no effect. It may have something to do with minimizing the game or switching windows… I can’t think of anything else I could have done that would contribute to a problem like this.